chore(deps): update actions/upload-artifact action to v7

Reviewed-on: #18

.gitea/workflows/test.yaml

@@ -0,0 +1,111 @@
+name: CI Tests
+
+on:
+  push:
+    branches:
+    - main
+  pull_request:
+    branches:
+    - main
+  workflow_dispatch:
+
+jobs:
+  unit-test:
+    name: JS Unit Tests
+    runs-on: k8s
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v7
+
+    - name: Run JS Unit Tests
+      shell: bash
+      run: node --test
+
+  test:
+    name: ${{ matrix.image_set.name }} (sbom=${{ matrix.use_inbuild_sbom }})
+    needs: unit-test
+    runs-on: k8s
+    strategy:
+      fail-fast: false
+      matrix:
+        image_set:
+          # Test 1: Slim images with built-in SBOMs (2 architectures, 15-40 CVEs each)
+        - name: with-inbuild-sbom
+          head_image: debian:bookworm-slim
+          target_image: debian:bullseye-slim
+          architectures: amd64,arm64
+          expect_arch_col: true
+
+          # Test 2: Slim images without built-in SBOMs (1 architecture, 70-120 CVEs each)
+        - name: without-inbuild-sbom
+          head_image: debian:buster-slim
+          target_image: debian:stretch-slim
+          architectures: amd64
+          expect_arch_col: false
+
+          # Test 3: Cross-check (Head has built-in SBOM, Target does not, 15-70 CVEs each)
+        - name: cross-check-mixed-sbom
+          head_image: debian:bookworm-slim
+          target_image: debian:buster-slim
+          architectures: amd64
+          expect_arch_col: false
+
+        use_inbuild_sbom:
+        - 'true'
+        - 'false'
+
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v7
+
+    - name: Test CVE Differential Action
+      uses: ./
+      with:
+        head-image: ${{ matrix.image_set.head_image }}
+        target-image: ${{ matrix.image_set.target_image }}
+        target-branch: main
+        architectures: ${{ matrix.image_set.architectures }}
+        use-inbuild-sbom: ${{ matrix.use_inbuild_sbom }}
+        output-delta: cve-delta.md
+        output-summary: cve-summary.md
+
+    - name: Verify Report Generation & Content
+      shell: bash
+      run: |
+        set -euo pipefail
+
+        test -s cve-delta.md || (echo "::error::cve-delta.md is empty or missing" && exit 1)
+        test -s cve-summary.md || (echo "::error::cve-summary.md is empty or missing" && exit 1)
+
+        # Verify that each scan produced at least 3 CVE findings
+        cve_count=$(grep -c "CVE-" cve-summary.md || echo 0)
+        echo "Total CVE entries found in summary report: $cve_count"
+        if [ "$cve_count" -lt 3 ]; then
+          echo "::error::Expected at least 3 CVEs in cve-summary.md, found only $cve_count"
+          exit 1
+        fi
+
+        echo "=== Delta Report Preview ==="
+        head -n 25 cve-delta.md
+
+        # Verify architectural column rendering behavior
+        if [ "${{ matrix.image_set.expect_arch_col }}" = "true" ]; then
+          grep -q "| Arch |" cve-delta.md || (echo "::error::Expected Arch column in multi-arch report" && exit 1)
+        else
+          if grep -q "| Arch |" cve-delta.md; then
+            echo "::error::Did not expect Arch column in single-arch report" && exit 1
+          fi
+        fi
+        echo "✅ All assertions passed (including >= 3 CVEs verification)."
+
+    - name: Archive SBOMs and CVE Reports
+      if: always()
+      uses: actions/upload-artifact@v7
+      with:
+        name: sboms-and-reports-${{ matrix.image_set.name }}-inbuild-${{ matrix.use_inbuild_sbom }}
+        path: |
+          sboms/
+          cve-reports/
+          cve-delta.md
+          cve-summary.md
+        if-no-files-found: ignore

.gitignore

@@ -13,3 +13,4 @@ cve-*.json
 cve-delta.md
 cve-summary.md
 node_modules/
+!test/fixtures/**

README.md

@@ -6,28 +6,28 @@ A self-contained Gitea and GitHub Actions composite action that extracts multi-p
 
 ## ✨ Features
 
-- **Multi-Platform Support**: Automatically detects and extracts SPDX SBOM attestations for multi arch images.
-- **Fast Attestation Extraction**: Uses `docker buildx imagetools inspect` to extract SBOMs directly from registry manifest indices in seconds without downloading layer blobs.
-- **Graceful Fallbacks**: If SBOM attestations or baseline images are missing, automatically falls back to generating SBOMs directly with Trivy. Using images that do contain an SBOM is highly recomended though!
+- **Dynamic Multi-Platform Support**: Automatically discovers and scans all architectures present in container images, or iterates over an explicit list of target architectures.
+- **Fast Attestation Extraction with Automatic Fallback**: Uses `docker buildx imagetools inspect` to extract platform-specific SBOMs directly from registry manifest indices. If attestations are missing or produce 0 CVE findings (common when third-party generators omit OS qualifiers in SPDX), it automatically falls back to generating SBOMs directly with Trivy per architecture.
 - **Set-Based Differential Analysis**: Categorizes vulnerabilities into:
   - 🔴 **Introduced Vulnerabilities** (newly added in this branch / commit)
   - 🟢 **Fixed Vulnerabilities** (present in target baseline, resolved in this branch)
   - ⚪ **Unchanged Vulnerabilities** (pre-existing in target baseline)
-- **Secure by Default**: Verified Trivy binary downloads against static SHA256 checksum lockfiles and single-step unified caching (binary + vulnerability database).
+- **Secure & Unit Tested**: Verified Trivy binary downloads against static SHA256 checksum lockfiles, single-step unified caching, and comprehensive native unit tests (`node:test`).
 
 ---
 
 ## 📥 Inputs
 
 | Input | Description | Required | Default |
-| :--- | :--- | :---: | :--- |
+| :--- | :--- | :--- | :--- |
 | `head-image` | Head container image reference to scan (e.g. `registry.example.com/repo:git-sha`) | **Yes** | — |
 | `target-image` | Target baseline container image reference to compare against (e.g. `registry.example.com/repo:latest`) | **Yes** | — |
 | `target-branch` | Target branch name for report headings | No | `main` |
-| `trivy-version` | Trivy version to install and verify | No | `0.74.0` |
+| `architectures` | Comma-separated architectures/platforms to scan (e.g. `amd64,arm64`). If omitted, scans all architectures present in the image. | No | _(all)_ |
 | `output-delta` | Output path for the CVE delta Markdown report | No | `cve-delta.md` |
 | `output-summary` | Output path for the full vulnerability Markdown summary | No | `cve-summary.md` |
 | `write-summary` | Whether to append the generated reports to the job summary (`$GITHUB_STEP_SUMMARY`) | No | `true` |
+| `use-inbuild-sbom` | Whether to inspect and use built-in image SBOM attestations. If false (recommended default), generates SBOMs directly with Trivy for maximum vulnerability fidelity. If true, extracts attestations without pulling layers (faster, but findings reflect binary-package SBOMs without rootfs source-mapping; falls back to Trivy image scan if 0 CVEs detected). | No | `false` |
 
 ---
 
@@ -40,6 +40,46 @@ A self-contained Gitea and GitHub Actions composite action that extracts multi-p
 
 ---
 
+## 🔍 Built-in SBOM Attestations vs. Trivy Direct Scanning (Syft vs. Trivy)
+
+This action supports two modes for obtaining SBOMs:
+
+### 1. Direct Image Scanning with Trivy (`use-inbuild-sbom: false` — Default & Recommended)
+By default, the action uses `trivy image --format spdx-json` to generate the SBOM directly from the container images:
+- **Full Filesystem Fidelity**: Inspects the entire flattened root filesystem, reading `/etc/os-release` and native package databases (e.g. `/var/lib/dpkg/status`, RPM databases, apk).
+- **Accurate OS & Language Package Detection**: Catalogs both OS packages (Debian, Alpine, RHEL, etc.) and application dependencies (Python, Node.js, Go, etc.).
+- **Symmetric, Apples-to-Apples Comparisons**: Both `head` and `target` images are analyzed using the identical Trivy engine and vulnerability database, preventing skewed diffs.
+
+### 2. Built-in Attestation Extraction with Resilient Fallback (`use-inbuild-sbom: true`)
+When enabled, the action extracts SBOM attestations attached to the container image using `docker buildx imagetools inspect`:
+- **Speed**: Extracts the SBOM JSON metadata directly from the registry manifest index in seconds without pulling image layer blobs.
+- **Underlying Generator (Syft / Docker Scout)**: Docker Buildx (`sbom: true`) uses BuildKit's embedded Syft scanner (`moby/buildkit-syft-scanner`).
+- **Distro Detection**: Automatically extracts OS distribution information from package PURLs (e.g. `debian/12`) and queries Trivy with `--distro` to accurately identify vulnerabilities on the extracted SBOM.
+- **Resilient Fallback**: If an extracted in-build SBOM scan produces 0 CVE findings (a common issue when third-party generators omit OS distribution qualifiers from SPDX packages) or if scanning fails, the action **automatically falls back** to running `trivy image --platform "$platform" --format spdx-json` directly on the image. This guarantees that vulnerability scans never fail silently or report false zeros.
+- **Audit Copies**: The action preserves copies of both the raw extracted in-build SBOM (`inbuild-sbom-*.spdx.json`) and the final scanned SBOM (`sbom-*.spdx.json`) for auditing and debugging.
+
+### ⚖️ Trade-offs: Why do the results differ between strategies?
+
+The vulnerability results between Strategy 1 (`sbom: false`) and Strategy 2 (`sbom: true`) are **not identical**:
+
+| Feature / Metric | Direct Trivy Scan (`use-inbuild-sbom: false`) | Built-in Attestation (`use-inbuild-sbom: true`) |
+| :--- | :--- | :--- |
+| **Generator** | Trivy directly on container rootfs | Docker Scout / BuildKit (Syft) |
+| **Execution Speed** | Slower (pulls image layer blobs) | **Very Fast** (~5x faster, 0 layer downloads) |
+| **Debian Slim Findings Example** | **~225 CVEs** (`debian:bookworm-slim`) | **~104 CVEs** (`debian:bookworm-slim`) |
+| **Package Resolution Model** | Source & binary packages (`/var/lib/dpkg/status`) | Binary packages cataloged in SPDX PURLs |
+| **Filesystem Inspection** | Full filesystem (static binaries, libraries) | Manifest-only (packages cataloged at build time) |
+| **Primary Use Case** | **High-fidelity security audits & release gates** | **High-speed PR checks & developer feedback loops** |
+
+#### Why the vulnerability counts differ:
+1. **Debian Source vs. Binary Packages**: Debian security advisories (DSAs / DLAs) are tracked and published per **source package** (e.g., the source package `glibc` produces multiple binary packages like `libc6`, `libc-bin`, `locales`). Trivy's filesystem scanner reads `/var/lib/dpkg/status` to map installed binary packages directly to Debian source package advisories. Syft's default SPDX output catalogs installed binary packages as PURLs without source-package relations, so Trivy's SBOM scan queries only the exact binary package entries that match Debian database schemas without the source-mapping context.
+2. **Filesystem vs. Manifest Scope**: Direct image scanning unpacks and inspects the entire container image filesystem (including file hashes, crypto libraries, and static binaries). An in-build SBOM scan is strictly limited to the package inventory written by the build-time generator.
+
+> [!TIP]
+> Setting `use-inbuild-sbom: 'false'` remains the recommended default for maximum accuracy and cross-platform consistency. If you choose to enable `use-inbuild-sbom: 'true'`, the built-in fallback ensures full coverage even when third-party attestations lack OS package metadata.
+
+---
+
 ## 🚀 Usage Example
 
 ```yaml
@@ -47,20 +87,16 @@ jobs:
   build-and-scan:
     runs-on: ubuntu-latest
     steps:
-      - name: Checkout repository
-        uses: actions/checkout@v4
       
       - name: Build and Push Head Container Image
         uses: docker/build-push-action@v5
         with:
           context: .
           push: true
-          sbom: true
-          platforms: linux/amd64,linux/arm64
           tags: registry.example.com/my-app:git-${{ github.sha }}
 
       - name: Compare Vulnerabilities (Head vs Target)
-        uses: https://git.horstenkamp.eu/Philipp/cve-differential@main
+        uses: https://git.horstenkamp.eu/Philipp/cve-differential.git@main
         with:
           head-image: registry.example.com/my-app:git-${{ github.sha }}
           target-image: registry.example.com/my-app:latest

action.yaml

@@ -12,10 +12,10 @@ inputs:
     description: Target branch name for delta heading (e.g. main)
     required: false
     default: main
-  trivy-version:
-    description: Trivy binary version to install and verify
+  architectures:
+    description: Comma-separated list of architectures or platforms to scan (e.g. 'amd64,arm64' or 'linux/amd64,linux/arm64'). If empty, scans all architectures found in the container image.
     required: false
-    default: 0.74.0   # trivy-version
+    default: ''
   output-delta:
     description: Output markdown file for CVE delta report
     required: false
@@ -28,6 +28,10 @@ inputs:
     description: Whether to append the generated reports to the job summary ($GITHUB_STEP_SUMMARY)
     required: false
     default: 'true'
+  use-inbuild-sbom:
+    description: Whether to inspect and use built-in image SBOM attestations. If false (recommended default), generates SBOMs directly with Trivy for maximum vulnerability detection fidelity. If true, extracts attestations without pulling layers (faster, but findings may differ from direct scans due to binary vs source package tracking; falls back to Trivy image scan if 0 CVEs detected).
+    required: false
+    default: 'false'
 
 outputs:
   delta-report:
@@ -40,41 +44,47 @@ outputs:
 runs:
   using: composite
   steps:
-  - name: Prepare Cache Keys
+  - name: Prepare Cache Keys and Environment
     id: vars
     shell: bash
-    run: echo "date=$(date -u +%Y-%m-%d)" >> "$GITHUB_OUTPUT"
+    env:
+      TRIVY_VERSION: 0.74.0   # trivy-version
+    run: |
+      echo "date=$(date -u +%Y-%m-%d)" >> "$GITHUB_OUTPUT"
+      echo "version=${TRIVY_VERSION}" >> "$GITHUB_OUTPUT"
 
   - name: Cache Trivy (Binary & Vulnerability DB)
-    uses: actions/cache@0057852bfaa89a56745cba8c7296529d2fc39830     # v4.3.0
+    uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9     # v6.1.0
     with:
       path: |
         ~/.cache/trivy-bin
         ~/.cache/trivy
-      key: trivy-${{ inputs.trivy-version }}-${{ runner.os }}-${{ runner.arch }}-${{ steps.vars.outputs.date }}
+      key: trivy-${{ steps.vars.outputs.version }}-${{ runner.os }}-${{ runner.arch }}-${{ steps.vars.outputs.date }}
       restore-keys: |
-        trivy-${{ inputs.trivy-version }}-${{ runner.os }}-${{ runner.arch }}-
+        trivy-${{ steps.vars.outputs.version }}-${{ runner.os }}-${{ runner.arch }}-
 
   - name: Install and Verify Trivy
     shell: bash
     run: |
-      mkdir -p "$HOME/.cache/trivy-bin" "$HOME/.local/bin"
-      echo "$HOME/.local/bin" >> "$GITHUB_PATH"
+      set -euo pipefail
 
-      ARCH=$(uname -m)
-      case "$ARCH" in
+      mkdir -p "$HOME/.local/bin" "$HOME/.cache/trivy-bin"
+      echo "$HOME/.local/bin" >> "$GITHUB_PATH"
+      ARCH="$(uname -m)"
+      case "${ARCH}" in
         x86_64) T_ARCH="64bit" ;;
         aarch64|arm64) T_ARCH="ARM64" ;;
-        *) echo "Unsupported architecture: $ARCH"; exit 1 ;;
+        *) echo "::error::Unsupported architecture: ${ARCH}"; exit 1 ;;
       esac
-      tarball="trivy_${{ inputs.trivy-version }}_Linux-${T_ARCH}.tar.gz"
+
       checksums_file="${{ github.action_path }}/checksums.txt"
+      tarball="trivy_${{ steps.vars.outputs.version }}_Linux-${T_ARCH}.tar.gz"
 
       if [ -f "$HOME/.cache/trivy-bin/${tarball}" ] && (cd "$HOME/.cache/trivy-bin" && grep "  ${tarball}$" "$checksums_file" | sha256sum -c -); then
         echo "Cached Trivy archive verified against lockfile."
       else
         echo "Archive missing or checksum mismatch; downloading..."
-        curl -sfLO "https://github.com/aquasecurity/trivy/releases/download/v${{ inputs.trivy-version }}/${tarball}" --output-dir "$HOME/.cache/trivy-bin"
+        curl -sfLO "https://github.com/aquasecurity/trivy/releases/download/v${{ steps.vars.outputs.version }}/${tarball}" --output-dir "$HOME/.cache/trivy-bin"
         (cd "$HOME/.cache/trivy-bin" && grep "  ${tarball}$" "$checksums_file" | sha256sum -c -)
       fi
 
@@ -85,108 +95,449 @@ runs:
     shell: bash
     run: |
       export PATH="$HOME/.local/bin:$PATH"
+      export TRIVY_SKIP_VERSION_CHECK="true"
       mkdir -p sboms/head sboms/target
 
       cleanup_file() {
         local f="$1"
+        if [ -f "$f" ]; then
           if [ ! -s "$f" ] || [ "$(cat "$f" 2>/dev/null)" = "null" ]; then
             rm -f "$f"
           fi
+        fi
       }
 
-      # Extract platform SBOMs for head image
-      echo "Extracting platform SBOMs for head image: ${{ inputs.head-image }}..."
-      docker buildx imagetools inspect "${{ inputs.head-image }}" \
-        --format '{{ json (index .SBOM "linux/amd64").SPDX }}' > sboms/head/sbom-amd64.spdx.json 2>/dev/null || true
-      cleanup_file sboms/head/sbom-amd64.spdx.json
+      head_sbom_err=""
+      target_sbom_err=""
+      use_inbuild="${{ inputs.use-inbuild-sbom }}"
 
-      docker buildx imagetools inspect "${{ inputs.head-image }}" \
-        --format '{{ json (index .SBOM "linux/arm64").SPDX }}' > sboms/head/sbom-arm64.spdx.json 2>/dev/null || true
-      cleanup_file sboms/head/sbom-arm64.spdx.json
+      # Determine target platforms / architectures
+      PLATFORMS=()
+      if [ -n "${{ inputs.architectures }}" ]; then
+        IFS=',' read -ra RAW_ARCHS <<< "${{ inputs.architectures }}"
+        for a in "${RAW_ARCHS[@]}"; do
+          clean_a=$(echo "$a" | xargs)
+          [ -z "$clean_a" ] && continue
+          if [[ "$clean_a" != *"/"* ]]; then
+            PLATFORMS+=("linux/${clean_a}")
+          else
+            PLATFORMS+=("$clean_a")
+          fi
+        done
+      else
+        echo "Auto-discovering architectures from images..."
+        raw_head=$(docker buildx imagetools inspect --raw "${{ inputs.head-image }}" 2>/dev/null || true)
+        raw_target=$(docker buildx imagetools inspect --raw "${{ inputs.target-image }}" 2>/dev/null || true)
 
-      # If single-arch, extract root .SPDX
-      if [ ! -f sboms/head/sbom-amd64.spdx.json ] && [ ! -f sboms/head/sbom-arm64.spdx.json ]; then
-        docker buildx imagetools inspect "${{ inputs.head-image }}" \
-          --format '{{ json .SBOM.SPDX }}' > sboms/head/sbom-amd64.spdx.json 2>/dev/null || true
-        cleanup_file sboms/head/sbom-amd64.spdx.json
+        discovered=$(node -e '
+          const raw1 = process.argv[1];
+          const raw2 = process.argv[2];
+          const set = new Set();
+          for (const raw of [raw1, raw2]) {
+            if (!raw) continue;
+            try {
+              const data = JSON.parse(raw);
+              const manifests = data.manifests || [];
+              for (const m of manifests) {
+                if (m.platform && m.platform.architecture && m.platform.architecture !== "unknown") {
+                  const os = m.platform.os || "linux";
+                  const variant = m.platform.variant ? "/" + m.platform.variant : "";
+                  set.add(`${os}/${m.platform.architecture}${variant}`);
+                }
+              }
+            } catch (e) {}
+          }
+          console.log(Array.from(set).sort().join("\n"));
+        ' "$raw_head" "$raw_target")
+
+        if [ -n "$discovered" ]; then
+          while IFS= read -r line; do
+            [ -n "$line" ] && PLATFORMS+=("$line")
+          done <<< "$discovered"
+        fi
       fi
 
-      # Fallback to generating head SBOM with Trivy if attestation missing
-      if [ ! -f sboms/head/sbom-amd64.spdx.json ] && [ ! -f sboms/head/sbom-arm64.spdx.json ]; then
-        echo "Head image lacks SBOM attestation; generating with Trivy..."
-        trivy image --format spdx-json --output sboms/head/sbom-amd64.spdx.json "${{ inputs.head-image }}" || true
-        cleanup_file sboms/head/sbom-amd64.spdx.json
+      echo "Configured platforms: ${PLATFORMS[*]:-(single platform fallback)}"
+      if [ "$use_inbuild" = "true" ]; then
+        echo "ℹ️  Strategy: Built-in SBOM attestation extraction enabled (Docker Scout / Syft). Skips container layer downloads for maximum speed."
+        echo "ℹ️  Note: Built-in SBOM vulnerability counts may differ from direct filesystem scans ('trivy image') due to binary vs. source package tracking."
+      else
+        echo "ℹ️  Strategy: Direct Trivy image scanning enabled (default). Inspects full container rootfs and package databases for maximum fidelity."
       fi
 
-      # Extract platform SBOMs for target image
-      echo "Extracting platform SBOMs for target image: ${{ inputs.target-image }}..."
-      docker buildx imagetools inspect "${{ inputs.target-image }}" \
-        --format '{{ json (index .SBOM "linux/amd64").SPDX }}' > sboms/target/sbom-amd64.spdx.json 2>/dev/null || true
-      cleanup_file sboms/target/sbom-amd64.spdx.json
+      for platform in "${PLATFORMS[@]}"; do
+        arch_tag=$(echo "$platform" | sed -e 's#^[a-zA-Z0-9_-]*/##' -e 's#/#-#g')
 
-      docker buildx imagetools inspect "${{ inputs.target-image }}" \
-        --format '{{ json (index .SBOM "linux/arm64").SPDX }}' > sboms/target/sbom-arm64.spdx.json 2>/dev/null || true
-      cleanup_file sboms/target/sbom-arm64.spdx.json
-
-      if [ ! -f sboms/target/sbom-amd64.spdx.json ] && [ ! -f sboms/target/sbom-arm64.spdx.json ]; then
-        docker buildx imagetools inspect "${{ inputs.target-image }}" \
-          --format '{{ json .SBOM.SPDX }}' > sboms/target/sbom-amd64.spdx.json 2>/dev/null || true
-        cleanup_file sboms/target/sbom-amd64.spdx.json
+        # Head image extraction & fallback
+        if [ "$use_inbuild" = "true" ]; then
+          echo "Attempting extraction of built-in SBOM for head image ($platform)..."
+          docker buildx imagetools inspect "${{ inputs.head-image }}" \
+            --format "{{ json (index .SBOM \"${platform}\").SPDX }}" > "sboms/head/sbom-${arch_tag}.spdx.json" 2>/dev/null || true
+          cleanup_file "sboms/head/sbom-${arch_tag}.spdx.json"
+          [ -f "sboms/head/sbom-${arch_tag}.spdx.json" ] && cp "sboms/head/sbom-${arch_tag}.spdx.json" "sboms/head/inbuild-sbom-${arch_tag}.spdx.json" 2>/dev/null || true
         fi
 
-      # Fallback to generating target SBOM with Trivy if attestation missing
-      if [ ! -f sboms/target/sbom-amd64.spdx.json ] && [ ! -f sboms/target/sbom-arm64.spdx.json ]; then
-        echo "Target image lacks SBOM attestation; attempting to generate with Trivy..."
-        trivy image --format spdx-json --output sboms/target/sbom-amd64.spdx.json "${{ inputs.target-image }}" || true
-        cleanup_file sboms/target/sbom-amd64.spdx.json
+        if [ ! -f "sboms/head/sbom-${arch_tag}.spdx.json" ]; then
+          echo "Generating SBOM for head image ($platform) with Trivy..."
+          if ! trivy image --skip-version-check --platform "$platform" --format spdx-json --output "sboms/head/sbom-${arch_tag}.spdx.json" "${{ inputs.head-image }}"; then
+            echo "::warning::Trivy image scan failed for head image ($platform)"
+          fi
+          cleanup_file "sboms/head/sbom-${arch_tag}.spdx.json"
+        fi
+
+        # Target image extraction & fallback
+        if [ "$use_inbuild" = "true" ]; then
+          echo "Attempting extraction of built-in SBOM for target image ($platform)..."
+          docker buildx imagetools inspect "${{ inputs.target-image }}" \
+            --format "{{ json (index .SBOM \"${platform}\").SPDX }}" > "sboms/target/sbom-${arch_tag}.spdx.json" 2>/dev/null || true
+          cleanup_file "sboms/target/sbom-${arch_tag}.spdx.json"
+          [ -f "sboms/target/sbom-${arch_tag}.spdx.json" ] && cp "sboms/target/sbom-${arch_tag}.spdx.json" "sboms/target/inbuild-sbom-${arch_tag}.spdx.json" 2>/dev/null || true
+        fi
+
+        if [ ! -f "sboms/target/sbom-${arch_tag}.spdx.json" ]; then
+          echo "Generating SBOM for target image ($platform) with Trivy..."
+          if ! trivy image --skip-version-check --platform "$platform" --format spdx-json --output "sboms/target/sbom-${arch_tag}.spdx.json" "${{ inputs.target-image }}"; then
+            echo "::warning::Trivy image scan failed for target image ($platform)"
+          fi
+          cleanup_file "sboms/target/sbom-${arch_tag}.spdx.json"
+        fi
+      done
+
+      # Fallbacks if no platform-specific SBOMs were extracted (e.g. single-arch image without index)
+      if [ -z "$(find sboms/head -type f -name 'sbom-*.spdx.json' 2>/dev/null)" ]; then
+        if [ "$use_inbuild" = "true" ]; then
+          docker buildx imagetools inspect "${{ inputs.head-image }}" \
+            --format '{{ json .SBOM.SPDX }}' > sboms/head/sbom-default.spdx.json 2>/dev/null || true
+          cleanup_file sboms/head/sbom-default.spdx.json
+          [ -f sboms/head/sbom-default.spdx.json ] && cp sboms/head/sbom-default.spdx.json sboms/head/inbuild-sbom-default.spdx.json 2>/dev/null || true
+        fi
+
+        if [ ! -f sboms/head/sbom-default.spdx.json ]; then
+          echo "Generating default head SBOM directly with Trivy..."
+          if ! trivy image --skip-version-check --format spdx-json --output sboms/head/sbom-default.spdx.json "${{ inputs.head-image }}"; then
+            head_sbom_err="Failed to generate SBOM with Trivy for head image"
+          fi
+          cleanup_file sboms/head/sbom-default.spdx.json
+        fi
+      fi
+
+      if [ -z "$(find sboms/target -type f -name 'sbom-*.spdx.json' 2>/dev/null)" ]; then
+        if [ "$use_inbuild" = "true" ]; then
+          docker buildx imagetools inspect "${{ inputs.target-image }}" \
+            --format '{{ json .SBOM.SPDX }}' > sboms/target/sbom-default.spdx.json 2>/dev/null || true
+          cleanup_file sboms/target/sbom-default.spdx.json
+          [ -f sboms/target/sbom-default.spdx.json ] && cp sboms/target/sbom-default.spdx.json sboms/target/inbuild-sbom-default.spdx.json 2>/dev/null || true
+        fi
+
+        if [ ! -f sboms/target/sbom-default.spdx.json ]; then
+          echo "Generating default target SBOM directly with Trivy..."
+          if ! trivy image --skip-version-check --format spdx-json --output sboms/target/sbom-default.spdx.json "${{ inputs.target-image }}"; then
+            target_sbom_err="Failed to generate SBOM with Trivy for target image"
+          fi
+          cleanup_file sboms/target/sbom-default.spdx.json
+        fi
+      fi
+
+      shopt -s nullglob
+      head_files=(sboms/head/sbom-*.spdx.json)
+      target_files=(sboms/target/sbom-*.spdx.json)
+
+      if [ ${#head_files[@]} -eq 0 ] && [ -z "$head_sbom_err" ]; then
+        head_sbom_err="No SBOM generated and head image could not be inspected"
+      fi
+
+      if [ ${#target_files[@]} -eq 0 ] && [ -z "$target_sbom_err" ]; then
+        target_sbom_err="No SBOM generated and target baseline image could not be inspected"
+      fi
+
+      # Diagnostic overview
+      echo ""
+      echo "================================================================================"
+      echo "                      SBOM EXTRACTION DIAGNOSTIC OVERVIEW                       "
+      echo "================================================================================"
+      if [ -n "$head_sbom_err" ]; then
+        echo "HEAD Image (${{ inputs.head-image }}): ❌ FAILED - $head_sbom_err"
+      else
+        echo "HEAD Image (${{ inputs.head-image }}): ✅ SUCCESS"
+        for f in "${head_files[@]}"; do
+          echo "  - $(basename "$f") ($(wc -c < "$f") bytes)"
+        done
+      fi
+
+      if [ -n "$target_sbom_err" ]; then
+        echo "TARGET Baseline Image (${{ inputs.target-image }}): ❌ FAILED - $target_sbom_err"
+      else
+        echo "TARGET Baseline Image (${{ inputs.target-image }}): ✅ SUCCESS"
+        for f in "${target_files[@]}"; do
+          echo "  - $(basename "$f") ($(wc -c < "$f") bytes)"
+        done
+      fi
+      echo "================================================================================"
+      echo ""
+
+      has_sbom_err=false
+      if [ -n "$head_sbom_err" ]; then
+        echo "::error::Head SBOM extraction failed: $head_sbom_err"
+        has_sbom_err=true
+      fi
+      if [ -n "$target_sbom_err" ]; then
+        echo "::error::Target baseline SBOM extraction failed: $target_sbom_err"
+        has_sbom_err=true
+      fi
+
+      if [ "$has_sbom_err" = "true" ]; then
+        echo "::error::Both head and target images must have valid SBOMs to proceed with differential scanning."
+        exit 1
       fi
 
       # Expose extracted head SBOMs to workspace root for workflow artifact uploads
-      [ -f sboms/head/sbom-amd64.spdx.json ] && cp sboms/head/sbom-amd64.spdx.json sbom-amd64.spdx.json || true
-      [ -f sboms/head/sbom-arm64.spdx.json ] && cp sboms/head/sbom-arm64.spdx.json sbom-arm64.spdx.json || true
+      for f in sboms/head/sbom-*.spdx.json; do
+        [ -f "$f" ] || continue
+        cp "$f" "$(basename "$f")" || true
+      done
 
   - name: Scan Multi-Platform SBOMs and Generate Delta
     shell: bash
     run: |
       export PATH="$HOME/.local/bin:$PATH"
+      export TRIVY_SKIP_VERSION_CHECK="true"
       mkdir -p cve-reports/head cve-reports/target
 
-      # Scan each available head SBOM
-      for f in sboms/head/sbom-*.spdx.json; do
-        [ -f "$f" ] || continue
+      shopt -s nullglob
+      head_sboms=(sboms/head/sbom-*.spdx.json)
+      target_sboms=(sboms/target/sbom-*.spdx.json)
+
+      head_ok=true
+      target_ok=true
+      head_report_count=0
+      target_report_count=0
+
+      head_summary=()
+      target_summary=()
+      use_inbuild="${{ inputs.use-inbuild-sbom }}"
+
+      detect_distro() {
+        node -e '
+          const fs = require("fs");
+          try {
+            const data = JSON.parse(fs.readFileSync(process.argv[1], "utf8"));
+            let name, ver;
+            for (const pkg of (data.packages || [])) {
+              for (const ref of (pkg.externalRefs || [])) {
+                if (ref.referenceType === "purl" && ref.referenceLocator) {
+                  const mName = ref.referenceLocator.match(/[?&]os_name=([^&]+)/);
+                  const mVer = ref.referenceLocator.match(/[?&]os_version=([^&]+)/);
+                  if (mName && mVer) {
+                    name = mName[1];
+                    ver = mVer[1];
+                    break;
+                  }
+                }
+              }
+              if (name && ver) break;
+            }
+            if (name && ver) console.log(name + "/" + ver);
+          } catch (e) {}
+        ' "$1" 2>/dev/null || true
+      }
+
+      # 1. Scan Head SBOMs
+      if [ ${#head_sboms[@]} -eq 0 ]; then
+        head_ok=false
+        head_summary+=("  - ❌ No SBOM files found in sboms/head/")
+      else
+        for f in "${head_sboms[@]}"; do
           arch=$(basename "$f" .spdx.json | sed 's/sbom-//')
+          out_json="cve-reports/head/cve-${arch}.json"
+          err_log="cve-reports/head/cve-${arch}.err"
+
           echo "Scanning head SBOM for architecture: $arch"
-        trivy sbom --format json --output "cve-reports/head/cve-${arch}.json" "$f" || true
-      done
-
-      # Scan each available target SBOM
-      for f in sboms/target/sbom-*.spdx.json; do
-        [ -f "$f" ] || continue
-        arch=$(basename "$f" .spdx.json | sed 's/sbom-//')
-        echo "Scanning target SBOM for architecture: $arch"
-        trivy sbom --format json --output "cve-reports/target/cve-${arch}.json" "$f" || true
-      done
-
-      # Run multi-arch set-based diff
-      node "${{ github.action_path }}/cve-diff.js" \
-        "cve-reports/target" \
-        "cve-reports/head" \
-        "${{ inputs.target-branch }}" > "${{ inputs.output-delta }}" || true
-
-      # Generate full markdown summary report for primary platform
-      primary_sbom=""
-      if [ -f sboms/head/sbom-amd64.spdx.json ]; then
-        primary_sbom="sboms/head/sbom-amd64.spdx.json"
-      elif [ -f sboms/head/sbom-arm64.spdx.json ]; then
-        primary_sbom="sboms/head/sbom-arm64.spdx.json"
+          distro_arg=""
+          if [ "$use_inbuild" = "true" ]; then
+            detected_distro=$(detect_distro "$f")
+            if [ -n "$detected_distro" ]; then
+              echo "Detected distribution '${detected_distro}' from in-build SBOM PURLs. Scanning with --distro."
+              distro_arg="--distro ${detected_distro}"
+            fi
           fi
 
-      if [ -n "$primary_sbom" ]; then
-        trivy sbom \
-          --format template \
-          --template "@${{ github.action_path }}/markdown.tpl" \
-          --output "${{ inputs.output-summary }}" \
-          "$primary_sbom" || true
+          scan_success=false
+          if trivy sbom $distro_arg --skip-version-check --format json --output "$out_json" "$f" 2>"$err_log"; then
+            scan_success=true
+          fi
+
+          vuln_cnt=0
+          if [ -s "$out_json" ]; then
+            cnt=$(grep -c '"VulnerabilityID"' "$out_json" 2>/dev/null || true)
+            cnt=$(echo "$cnt" | tr -d '[:space:]')
+            [ -n "$cnt" ] && vuln_cnt="$cnt"
+          fi
+
+          # Fallback if in-build SBOM scan produced 0 CVEs (e.g. incompatible third-party format) or scan failed
+          if [ "$use_inbuild" = "true" ] && { [ "$scan_success" != "true" ] || [ "$vuln_cnt" -eq 0 ]; }; then
+            echo "::warning::In-build SBOM for head image (${arch}) yielded ${vuln_cnt} CVE findings. Falling back to direct Trivy image scan..."
+            t_plat="linux/${arch}"
+            [ "$arch" = "default" ] && t_plat=""
+            plat_arg=""
+            [ -n "$t_plat" ] && plat_arg="--platform $t_plat"
+            if trivy image --skip-version-check $plat_arg --format spdx-json --output "$f" "${{ inputs.head-image }}"; then
+              echo "Re-scanning head SBOM generated directly by Trivy..."
+              if trivy sbom --skip-version-check --format json --output "$out_json" "$f" 2>"$err_log"; then
+                scan_success=true
+                if [ -s "$out_json" ]; then
+                  cnt=$(grep -c '"VulnerabilityID"' "$out_json" 2>/dev/null || true)
+                  cnt=$(echo "$cnt" | tr -d '[:space:]')
+                  [ -n "$cnt" ] && vuln_cnt="$cnt"
+                fi
+              fi
+            fi
+          fi
+
+          if [ "$scan_success" = "true" ]; then
+            if [ -s "$out_json" ]; then
+              if [ "$vuln_cnt" -eq 0 ]; then
+                echo "::warning::Head image architecture '${arch}' has 0 CVE findings. Verify that OS/packages were recognized."
+                head_summary+=("  - ${arch}: ⚠️ WARNING (0 vulnerability findings detected)")
+              else
+                head_summary+=("  - ${arch}: ✅ OK (${vuln_cnt} vulnerability findings)")
+              fi
+              head_report_count=$((head_report_count + 1))
+            else
+              head_ok=false
+              head_summary+=("  - ${arch}: ❌ FAILED (Output report was empty / 0 bytes)")
+            fi
+          else
+            head_ok=false
+            err_msg=$(tail -n 2 "$err_log" | tr '\n' ' ' | sed 's/  */ /g')
+            [ -z "$err_msg" ] && err_msg="Trivy scan exited with non-zero status"
+            head_summary+=("  - ${arch}: ❌ FAILED (${err_msg})")
+          fi
+        done
+      fi
+
+      # 2. Scan Target SBOMs
+      if [ ${#target_sboms[@]} -eq 0 ]; then
+        target_ok=false
+        target_summary+=("  - ❌ No SBOM files found in sboms/target/")
+      else
+        for f in "${target_sboms[@]}"; do
+          arch=$(basename "$f" .spdx.json | sed 's/sbom-//')
+          out_json="cve-reports/target/cve-${arch}.json"
+          err_log="cve-reports/target/cve-${arch}.err"
+
+          echo "Scanning target SBOM for architecture: $arch"
+          distro_arg=""
+          if [ "$use_inbuild" = "true" ]; then
+            detected_distro=$(detect_distro "$f")
+            if [ -n "$detected_distro" ]; then
+              echo "Detected distribution '${detected_distro}' from in-build SBOM PURLs. Scanning with --distro."
+              distro_arg="--distro ${detected_distro}"
+            fi
+          fi
+
+          scan_success=false
+          if trivy sbom $distro_arg --skip-version-check --format json --output "$out_json" "$f" 2>"$err_log"; then
+            scan_success=true
+          fi
+
+          vuln_cnt=0
+          if [ -s "$out_json" ]; then
+            cnt=$(grep -c '"VulnerabilityID"' "$out_json" 2>/dev/null || true)
+            cnt=$(echo "$cnt" | tr -d '[:space:]')
+            [ -n "$cnt" ] && vuln_cnt="$cnt"
+          fi
+
+          # Fallback if in-build SBOM scan produced 0 CVEs (e.g. incompatible third-party format) or scan failed
+          if [ "$use_inbuild" = "true" ] && { [ "$scan_success" != "true" ] || [ "$vuln_cnt" -eq 0 ]; }; then
+            echo "::warning::In-build SBOM for target image (${arch}) yielded ${vuln_cnt} CVE findings. Falling back to direct Trivy image scan..."
+            t_plat="linux/${arch}"
+            [ "$arch" = "default" ] && t_plat=""
+            plat_arg=""
+            [ -n "$t_plat" ] && plat_arg="--platform $t_plat"
+            if trivy image --skip-version-check $plat_arg --format spdx-json --output "$f" "${{ inputs.target-image }}"; then
+              echo "Re-scanning target SBOM generated directly by Trivy..."
+              if trivy sbom --skip-version-check --format json --output "$out_json" "$f" 2>"$err_log"; then
+                scan_success=true
+                if [ -s "$out_json" ]; then
+                  cnt=$(grep -c '"VulnerabilityID"' "$out_json" 2>/dev/null || true)
+                  cnt=$(echo "$cnt" | tr -d '[:space:]')
+                  [ -n "$cnt" ] && vuln_cnt="$cnt"
+                fi
+              fi
+            fi
+          fi
+
+          if [ "$scan_success" = "true" ]; then
+            if [ -s "$out_json" ]; then
+              if [ "$vuln_cnt" -eq 0 ]; then
+                echo "::warning::Target baseline image architecture '${arch}' has 0 CVE findings. Verify that OS/packages were recognized."
+                target_summary+=("  - ${arch}: ⚠️ WARNING (0 vulnerability findings detected)")
+              else
+                target_summary+=("  - ${arch}: ✅ OK (${vuln_cnt} vulnerability findings)")
+              fi
+              target_report_count=$((target_report_count + 1))
+            else
+              target_ok=false
+              target_summary+=("  - ${arch}: ❌ FAILED (Output report was empty / 0 bytes)")
+            fi
+          else
+            target_ok=false
+            err_msg=$(tail -n 2 "$err_log" | tr '\n' ' ' | sed 's/  */ /g')
+            [ -z "$err_msg" ] && err_msg="Trivy scan exited with non-zero status"
+            target_summary+=("  - ${arch}: ❌ FAILED (${err_msg})")
+          fi
+        done
+      fi
+
+      # 3. Print Comprehensive Diagnostic Overview
+      echo ""
+      echo "================================================================================"
+      echo "                   CVE VULNERABILITY SCAN DIAGNOSTIC OVERVIEW                  "
+      echo "================================================================================"
+      if [ "$use_inbuild" = "true" ]; then
+        echo "Scan Strategy: Built-in OCI Attestation (Syft/Docker Scout) with distro detection"
+      else
+        echo "Scan Strategy: Direct Trivy Image Scan (Full rootfs & source package mapping)"
+      fi
+      echo "--------------------------------------------------------------------------------"
+      echo "HEAD Image: ${{ inputs.head-image }}"
+      for line in "${head_summary[@]}"; do
+        echo "$line"
+      done
+      echo ""
+      echo "TARGET Baseline Image: ${{ inputs.target-image }} (branch: '${{ inputs.target-branch }}')"
+      for line in "${target_summary[@]}"; do
+        echo "$line"
+      done
+      echo "================================================================================"
+      echo ""
+
+      # 4. Enforce Gating: Both must have succeeded with valid reports
+      has_error=false
+      if [ "$head_ok" != "true" ] || [ "$head_report_count" -eq 0 ]; then
+        echo "::error::Head image CVE analysis failed or produced no reports."
+        has_error=true
+      fi
+
+      if [ "$target_ok" != "true" ] || [ "$target_report_count" -eq 0 ]; then
+        echo "::error::Target baseline CVE analysis failed or produced no reports."
+        has_error=true
+      fi
+
+      if [ "$has_error" = "true" ]; then
+        echo "::error::Aborting differential analysis: both head and target scans must succeed before diffing."
+        exit 1
+      fi
+
+      # 5. Run multi-arch set-based diff and generate consolidated full summary report
+      echo "Both head and target scans succeeded. Computing set-based vulnerability delta..."
+      if ! node "${{ github.action_path }}/cve-diff.js" \
+        "cve-reports/target" \
+        "cve-reports/head" \
+        "${{ inputs.target-branch }}" \
+        "${{ inputs.output-summary }}" > "${{ inputs.output-delta }}"; then
+        echo "::error::Failed to generate CVE differential report"
+        exit 1
       fi
 
   - name: Publish Reports to Step Summary

cve-diff.js

@@ -24,6 +24,7 @@ const SEVERITY_BADGES = {
  */
 function loadReportsForArg(arg) {
   const cves = new Map();
+  const scannedArchs = new Set();
   const filePaths = [];
 
   for (const part of arg.split(',').map((s) => s.trim())) {
@@ -41,36 +42,57 @@ function loadReportsForArg(arg) {
     }
   }
 
+  if (filePaths.length === 0) {
+    console.error(`::error::No CVE JSON report files found for path: ${arg}`);
+    process.exit(1);
+  }
+
+  let loadedFiles = 0;
   for (const filePath of filePaths) {
     let stat;
     try {
       stat = fs.statSync(filePath);
-    } catch {
-      continue;
+    } catch (e) {
+      console.error(`::error::Failed to access report file ${filePath}: ${e.message}`);
+      process.exit(1);
+    }
+    if (stat.size === 0) {
+      console.error(`::error::CVE report file is empty (0 bytes): ${filePath}`);
+      process.exit(1);
     }
-    if (stat.size === 0) continue;
 
-    const baseName = path.basename(filePath).toLowerCase();
+    const baseName = path.basename(filePath, '.json').toLowerCase();
     let arch = 'all';
-    if (baseName.includes('amd64')) {
+    const cveMatch = baseName.match(/^cve-([a-z0-9_.-]+)$/i);
+    if (cveMatch) {
+      arch = cveMatch[1];
+    } else if (baseName.includes('amd64')) {
       arch = 'amd64';
     } else if (baseName.includes('arm64') || baseName.includes('aarch64')) {
       arch = 'arm64';
     }
+    if (arch !== 'all') {
+      scannedArchs.add(arch);
+    }
 
     let data;
     try {
       const content = fs.readFileSync(filePath, 'utf8');
       data = JSON.parse(content);
-    } catch {
-      continue;
+    } catch (e) {
+      console.error(`::error::Invalid JSON in CVE report file ${filePath}: ${e.message}`);
+      process.exit(1);
     }
 
-    if (!data || typeof data !== 'object' || !Array.isArray(data.Results)) {
-      continue;
+    if (!data || typeof data !== 'object') {
+      console.error(`::error::Malformed Trivy report structure in: ${filePath}`);
+      process.exit(1);
     }
 
-    for (const result of data.Results) {
+    const results = Array.isArray(data.Results) ? data.Results : [];
+    loadedFiles++;
+
+    for (const result of results) {
       const target = result.Target || result.Type || 'App';
       const vulns = Array.isArray(result.Vulnerabilities) ? result.Vulnerabilities : [];
       for (const v of vulns) {
@@ -88,15 +110,23 @@ function loadReportsForArg(arg) {
     }
   }
 
+  if (loadedFiles === 0) {
+    console.error(`::error::No valid CVE reports could be loaded for path: ${arg}`);
+    process.exit(1);
+  }
+
+  cves.scannedArchs = scannedArchs;
   return cves;
 }
 
 /**
  * Formats a vulnerability record into a Markdown table row.
  * @param {object} v
+ * @param {Set<string>} [allScannedArchs]
+ * @param {boolean} [showArch]
  * @returns {string}
  */
-function formatVulnRow(v) {
+function formatVulnRow(v, allScannedArchs = new Set(), showArch = true) {
   const sev = v.Severity || 'UNKNOWN';
   const badge = SEVERITY_BADGES[sev] || `⚪ ${sev}`;
   const vid = v.VulnerabilityID || '';
@@ -104,22 +134,29 @@ function formatVulnRow(v) {
   const link = url ? `[${vid}](${url})` : vid;
   const pkg = v.PkgName || '';
 
-  const archs = v._archs || new Set(['all']);
-  let archBadge;
-  if ((archs.has('amd64') && archs.has('arm64')) || archs.has('all')) {
-    archBadge = '`all`';
-  } else {
-    archBadge = `\`${Array.from(archs).sort().join(', ')}\``;
-  }
-
   const installed = v.InstalledVersion || '-';
   const fixed = v.FixedVersion || '-';
-  let title = (v.Title || v.Description || '').replace(/\n/g, ' ').trim();
+  let title = (v.Title || v.Description || '').replace(/\n/g, ' ').replace(/\|/g, '\\|').trim();
   if (title.length > 80) {
     title = title.slice(0, 77) + '...';
   }
 
+  if (showArch) {
+    const archs = v._archs || new Set(['all']);
+    let archBadge;
+    if (
+      archs.has('all') ||
+      (allScannedArchs && allScannedArchs.size > 1 && archs.size === allScannedArchs.size) ||
+      (archs.has('amd64') && archs.has('arm64'))
+    ) {
+      archBadge = '`all`';
+    } else {
+      archBadge = `\`${Array.from(archs).sort().join(', ')}\``;
+    }
     return `| ${badge} | ${link} | \`${pkg}\` | ${archBadge} | ${installed} | ${fixed} | ${title} |`;
+  }
+
+  return `| ${badge} | ${link} | \`${pkg}\` | ${installed} | ${fixed} | ${title} |`;
 }
 
 /**
@@ -130,19 +167,17 @@ function formatVulnRow(v) {
  * @returns {string}
  */
 function renderMarkdownDiff(baseCves, branchCves, baseName = 'main') {
-  if (baseCves.size === 0) {
-    return [
-      `### 🔄 Vulnerability Delta (vs \`${baseName}\`)`,
-      '',
-      '> [!NOTE]',
-      `> No baseline scan from \`${baseName}\` was available to compare against.`,
-      '',
-    ].join('\n');
-  }
-
   const baseKeys = new Set(baseCves.keys());
   const branchKeys = new Set(branchCves.keys());
 
+  if (branchCves.size === 0) {
+    console.error('::warning::Head image contains 0 reported vulnerabilities. Verify that packages and dependencies were recognized.');
+  }
+
+  if (baseCves.size === 0) {
+    console.error(`::warning::Baseline target (${baseName}) contains 0 reported vulnerabilities.`);
+  }
+
   const newKeys = [];
   let unchangedCount = 0;
   for (const key of branchKeys) {
@@ -171,26 +206,52 @@ function renderMarkdownDiff(baseCves, branchCves, baseName = 'main') {
     return aPkg.localeCompare(bPkg);
   }
 
+  const allScannedArchs = new Set([
+    ...(baseCves.scannedArchs || []),
+    ...(branchCves.scannedArchs || []),
+  ]);
+  const showArch = allScannedArchs.size > 1;
+
   const newVulns = newKeys.map((k) => branchCves.get(k)).sort(sortVulns);
   const resolvedVulns = resolvedKeys.map((k) => baseCves.get(k)).sort(sortVulns);
 
   const lines = [
     `### 🔄 Vulnerability Delta (vs \`${baseName}\`)`,
     '',
-    '| Metric | Count |',
-    '| :--- | :--- |',
-    `| 🚨 **New Vulnerabilities** | ${newVulns.length > 0 ? `🚨 **${newVulns.length}**` : '0'} |`,
-    `| ✅ **Resolved Vulnerabilities** | ${resolvedVulns.length > 0 ? `✅ **${resolvedVulns.length}**` : '0'} |`,
-    `| ⚪ **Unchanged Vulnerabilities** | ${unchangedCount} |`,
-    '',
-    `#### 🚨 New Vulnerabilities Introduced (${newVulns.length})`,
   ];
 
+  if (branchCves.size === 0 && baseCves.size === 0) {
+    lines.push('> [!WARNING]');
+    lines.push('> Both the head image and baseline target have **0 reported vulnerabilities**.');
+    lines.push('');
+  } else if (branchCves.size === 0) {
+    lines.push('> [!WARNING]');
+    lines.push('> The head image has **0 reported vulnerabilities**. Verify that OS packages and language dependencies were properly indexed in the SBOM.');
+    lines.push('');
+  } else if (baseCves.size === 0) {
+    lines.push('> [!WARNING]');
+    lines.push(`> The baseline image (\`${baseName}\`) has **0 reported vulnerabilities**.`);
+    lines.push('');
+  }
+
+  lines.push('| Metric | Count |');
+  lines.push('| :--- | :--- |');
+  lines.push(`| 🚨 **New Vulnerabilities** | ${newVulns.length > 0 ? `🚨 **${newVulns.length}**` : '0'} |`);
+  lines.push(`| ✅ **Resolved Vulnerabilities** | ${resolvedVulns.length > 0 ? `✅ **${resolvedVulns.length}**` : '0'} |`);
+  lines.push(`| ⚪ **Unchanged Vulnerabilities** | ${unchangedCount} |`);
+  lines.push('');
+  lines.push(`#### 🚨 New Vulnerabilities Introduced (${newVulns.length})`);
+
   if (newVulns.length > 0) {
+    if (showArch) {
       lines.push('| Severity | CVE | Package | Arch | Installed | Fixed In | Title |');
       lines.push('| :--- | :--- | :--- | :--- | :--- | :--- | :--- |');
+    } else {
+      lines.push('| Severity | CVE | Package | Installed | Fixed In | Title |');
+      lines.push('| :--- | :--- | :--- | :--- | :--- | :--- |');
+    }
     for (const v of newVulns) {
-      lines.push(formatVulnRow(v));
+      lines.push(formatVulnRow(v, allScannedArchs, showArch));
     }
   } else {
     lines.push('✅ No new vulnerabilities introduced in this build.');
@@ -199,10 +260,15 @@ function renderMarkdownDiff(baseCves, branchCves, baseName = 'main') {
 
   lines.push(`#### ✅ Resolved / Removed Vulnerabilities (${resolvedVulns.length})`);
   if (resolvedVulns.length > 0) {
+    if (showArch) {
       lines.push('| Severity | CVE | Package | Arch | Previously Installed | Fixed In | Title |');
       lines.push('| :--- | :--- | :--- | :--- | :--- | :--- | :--- |');
+    } else {
+      lines.push('| Severity | CVE | Package | Previously Installed | Fixed In | Title |');
+      lines.push('| :--- | :--- | :--- | :--- | :--- | :--- |');
+    }
     for (const v of resolvedVulns) {
-      lines.push(formatVulnRow(v));
+      lines.push(formatVulnRow(v, allScannedArchs, showArch));
     }
   } else {
     lines.push('⚪ No existing vulnerabilities were resolved.');
@@ -212,22 +278,82 @@ function renderMarkdownDiff(baseCves, branchCves, baseName = 'main') {
   return lines.join('\n');
 }
 
+/**
+ * Renders a full markdown summary report of all vulnerabilities in a scan.
+ * @param {Map<string, object>} cves
+ * @returns {string}
+ */
+function renderFullSummary(cves) {
+  const allScannedArchs = cves.scannedArchs || new Set();
+  const showArch = allScannedArchs.size > 1;
+
+  const lines = [
+    '### 🛡️ Security Scan Report',
+    '',
+  ];
+
+  if (cves.size === 0) {
+    lines.push('✅ No vulnerabilities found.');
+    lines.push('');
+    return lines.join('\n');
+  }
+
+  function sortVulns(a, b) {
+    const aSev = a.Severity || 'UNKNOWN';
+    const bSev = b.Severity || 'UNKNOWN';
+    const aIdx = SEVERITY_ORDER.indexOf(aSev) !== -1 ? SEVERITY_ORDER.indexOf(aSev) : 99;
+    const bIdx = SEVERITY_ORDER.indexOf(bSev) !== -1 ? SEVERITY_ORDER.indexOf(bSev) : 99;
+    if (aIdx !== bIdx) return aIdx - bIdx;
+    const aPkg = a.PkgName || '';
+    const bPkg = b.PkgName || '';
+    return aPkg.localeCompare(bPkg);
+  }
+
+  const sortedVulns = Array.from(cves.values()).sort(sortVulns);
+
+  lines.push(`| Metric | Count |`);
+  lines.push(`| :--- | :--- |`);
+  lines.push(`| Total Vulnerabilities | **${sortedVulns.length}** |`);
+  lines.push('');
+
+  if (showArch) {
+    lines.push('| Severity | CVE | Package | Arch | Installed | Fixed In | Title |');
+    lines.push('| :--- | :--- | :--- | :--- | :--- | :--- | :--- |');
+  } else {
+    lines.push('| Severity | CVE | Package | Installed | Fixed In | Title |');
+    lines.push('| :--- | :--- | :--- | :--- | :--- | :--- |');
+  }
+
+  for (const v of sortedVulns) {
+    lines.push(formatVulnRow(v, allScannedArchs, showArch));
+  }
+  lines.push('');
+
+  return lines.join('\n');
+}
+
 function main() {
   const args = process.argv.slice(2);
   if (args.length < 2) {
-    console.error('Usage: cve-diff.js <base_report(s)> <branch_report(s)> [base_name]');
+    console.error('Usage: cve-diff.js <base_report(s)> <branch_report(s)> [base_name] [summary_output_path]');
     process.exit(1);
   }
 
   const baseArg = args[0];
   const branchArg = args[1];
   const baseName = args[2] || 'main';
+  const summaryOutputPath = args[3];
 
   const baseCves = loadReportsForArg(baseArg);
   const branchCves = loadReportsForArg(branchArg);
 
   const output = renderMarkdownDiff(baseCves, branchCves, baseName);
   console.log(output);
+
+  if (summaryOutputPath) {
+    const summaryOutput = renderFullSummary(branchCves);
+    fs.writeFileSync(summaryOutputPath, summaryOutput, 'utf8');
+  }
 }
 
 if (require.main === module) {
@@ -238,4 +364,5 @@ module.exports = {
   loadReportsForArg,
   formatVulnRow,
   renderMarkdownDiff,
+  renderFullSummary,
 };

renovate.json

@@ -6,11 +6,11 @@
   "customManagers": [
     {
       "customType": "regex",
-      "fileMatch": [
-        "^action\\.ya?ml$"
+      "managerFilePatterns": [
+        "/^action\\.ya?ml$/"
       ],
       "matchStrings": [
-        "default:\\s*(?<currentValue>[0-9]+\\.[0-9]+\\.[0-9]+)\\s*#\\s*trivy-version"
+        "TRIVY_VERSION:\\s*(?<currentValue>[0-9]+\\.[0-9]+\\.[0-9]+)\\s*#\\s*trivy-version"
       ],
       "depNameTemplate": "aquasecurity/trivy",
       "datasourceTemplate": "github-releases",

test/cve-diff.test.js

@@ -0,0 +1,111 @@
+const test = require('node:test');
+const assert = require('node:assert/strict');
+const path = require('node:path');
+const {
+  loadReportsForArg,
+  formatVulnRow,
+  renderMarkdownDiff,
+  renderFullSummary,
+} = require('../cve-diff.js');
+
+const FIXTURES_DIR = path.join(__dirname, 'fixtures');
+
+test('loadReportsForArg loads valid reports and extracts multi-arch metadata', () => {
+  const targetDir = path.join(FIXTURES_DIR, 'target');
+  const cves = loadReportsForArg(targetDir);
+
+  assert.equal(cves.size, 2);
+  assert.ok(cves.has('CVE-2023-0001:::glibc'));
+  assert.ok(cves.has('CVE-2023-0002:::openssl'));
+
+  const glibc = cves.get('CVE-2023-0001:::glibc');
+  assert.equal(glibc.Severity, 'CRITICAL');
+  assert.deepEqual(Array.from(glibc._archs).sort(), ['amd64', 'arm64']);
+  assert.deepEqual(Array.from(cves.scannedArchs).sort(), ['amd64', 'arm64']);
+
+  const openssl = cves.get('CVE-2023-0002:::openssl');
+  assert.equal(openssl.Severity, 'HIGH');
+  assert.deepEqual(Array.from(openssl._archs), ['amd64']);
+});
+
+test('loadReportsForArg handles reports with missing or null Results array without crashing', () => {
+  const emptyDir = path.join(FIXTURES_DIR, 'empty');
+  const cves = loadReportsForArg(emptyDir);
+
+  assert.equal(cves.size, 0);
+});
+
+test('renderMarkdownDiff produces correct introduced, resolved, and unchanged sets', () => {
+  const targetDir = path.join(FIXTURES_DIR, 'target');
+  const headDir = path.join(FIXTURES_DIR, 'head');
+
+  const baseCves = loadReportsForArg(targetDir);
+  const branchCves = loadReportsForArg(headDir);
+
+  const diff = renderMarkdownDiff(baseCves, branchCves, 'main');
+
+  // Introduced: CVE-2023-0003 (curl)
+  assert.ok(diff.includes('New Vulnerabilities Introduced (1)'));
+  assert.ok(diff.includes('CVE-2023-0003'));
+  assert.ok(diff.includes('`curl`'));
+
+  // Resolved: CVE-2023-0001 (glibc)
+  assert.ok(diff.includes('Resolved / Removed Vulnerabilities (1)'));
+  assert.ok(diff.includes('CVE-2023-0001'));
+  assert.ok(diff.includes('`glibc`'));
+
+  // Unchanged count
+  assert.ok(diff.includes('| ⚪ **Unchanged Vulnerabilities** | 1 |'));
+
+  // Multi-arch is present in fixtures (amd64, arm64), so Arch column should be shown
+  assert.ok(diff.includes('| Arch |'));
+});
+
+test('renderMarkdownDiff hides Arch column when single architecture is scanned', () => {
+  const targetSingle = path.join(FIXTURES_DIR, 'target', 'cve-amd64.json');
+  const headSingle = path.join(FIXTURES_DIR, 'head', 'cve-amd64.json');
+
+  const baseCves = loadReportsForArg(targetSingle);
+  const branchCves = loadReportsForArg(headSingle);
+
+  const diff = renderMarkdownDiff(baseCves, branchCves, 'main');
+
+  assert.ok(!diff.includes('| Arch |'));
+  assert.ok(diff.includes('New Vulnerabilities Introduced (1)'));
+  assert.ok(diff.includes('Resolved / Removed Vulnerabilities (1)'));
+});
+
+test('renderFullSummary outputs summary table and lists all vulnerabilities', () => {
+  const headDir = path.join(FIXTURES_DIR, 'head');
+  const headCves = loadReportsForArg(headDir);
+
+  const summary = renderFullSummary(headCves);
+
+  assert.ok(summary.includes('### 🛡️ Security Scan Report'));
+  assert.ok(summary.includes('| Total Vulnerabilities | **2** |'));
+  assert.ok(summary.includes('CVE-2023-0002'));
+  assert.ok(summary.includes('CVE-2023-0003'));
+});
+
+test('formatVulnRow properly formats badge, architecture tag, and escape pipes', () => {
+  const vuln = {
+    Severity: 'CRITICAL',
+    VulnerabilityID: 'CVE-2023-0001',
+    PrimaryURL: 'https://avd.aquasec.com/nvd/cve-2023-0001',
+    PkgName: 'glibc',
+    InstalledVersion: '2.31',
+    FixedVersion: '2.32',
+    Title: 'A vulnerability with | pipe symbol',
+    _archs: new Set(['amd64']),
+  };
+
+  const allArchs = new Set(['amd64', 'arm64']);
+  const rowWithArch = formatVulnRow(vuln, allArchs, true);
+
+  assert.ok(rowWithArch.includes('🔴 CRITICAL'));
+  assert.ok(rowWithArch.includes('`amd64`'));
+  assert.ok(rowWithArch.includes('\\|')); // Pipe escaped
+
+  const rowWithoutArch = formatVulnRow(vuln, allArchs, false);
+  assert.ok(!rowWithoutArch.includes('`amd64`'));
+});

test/fixtures/empty/cve-amd64.json

@@ -0,0 +1,8 @@
+{
+  "SchemaVersion": 2,
+  "ArtifactName": "debian:bullseye-slim",
+  "ArtifactType": "spdx",
+  "Metadata": {
+    "OS": null
+  }
+}

test/fixtures/head/cve-amd64.json

@@ -0,0 +1,30 @@
+{
+  "SchemaVersion": 2,
+  "ArtifactName": "debian:bookworm-slim",
+  "ArtifactType": "container_image",
+  "Results": [
+    {
+      "Target": "debian:bookworm-slim (debian 12)",
+      "Class": "os-pkgs",
+      "Type": "debian",
+      "Vulnerabilities": [
+        {
+          "VulnerabilityID": "CVE-2023-0002",
+          "PkgName": "openssl",
+          "InstalledVersion": "1.1.1n-0+deb11u4",
+          "FixedVersion": "1.1.1n-0+deb11u5",
+          "Severity": "HIGH",
+          "Title": "Timing attack in OpenSSL"
+        },
+        {
+          "VulnerabilityID": "CVE-2023-0003",
+          "PkgName": "curl",
+          "InstalledVersion": "7.88.1-10",
+          "FixedVersion": "7.88.1-10+deb12u1",
+          "Severity": "MEDIUM",
+          "Title": "Buffer overflow in curl"
+        }
+      ]
+    }
+  ]
+}

test/fixtures/head/cve-arm64.json

@@ -0,0 +1,22 @@
+{
+  "SchemaVersion": 2,
+  "ArtifactName": "debian:bookworm-slim",
+  "ArtifactType": "container_image",
+  "Results": [
+    {
+      "Target": "debian:bookworm-slim (debian 12)",
+      "Class": "os-pkgs",
+      "Type": "debian",
+      "Vulnerabilities": [
+        {
+          "VulnerabilityID": "CVE-2023-0003",
+          "PkgName": "curl",
+          "InstalledVersion": "7.88.1-10",
+          "FixedVersion": "7.88.1-10+deb12u1",
+          "Severity": "MEDIUM",
+          "Title": "Buffer overflow in curl"
+        }
+      ]
+    }
+  ]
+}

test/fixtures/target/cve-amd64.json

@@ -0,0 +1,36 @@
+{
+  "SchemaVersion": 2,
+  "ArtifactName": "debian:bullseye-slim",
+  "ArtifactType": "container_image",
+  "Metadata": {
+    "OS": {
+      "Family": "debian",
+      "Name": "11"
+    }
+  },
+  "Results": [
+    {
+      "Target": "debian:bullseye-slim (debian 11)",
+      "Class": "os-pkgs",
+      "Type": "debian",
+      "Vulnerabilities": [
+        {
+          "VulnerabilityID": "CVE-2023-0001",
+          "PkgName": "glibc",
+          "InstalledVersion": "2.31-13+deb11u5",
+          "FixedVersion": "2.31-13+deb11u6",
+          "Severity": "CRITICAL",
+          "Title": "Memory corruption in glibc"
+        },
+        {
+          "VulnerabilityID": "CVE-2023-0002",
+          "PkgName": "openssl",
+          "InstalledVersion": "1.1.1n-0+deb11u4",
+          "FixedVersion": "1.1.1n-0+deb11u5",
+          "Severity": "HIGH",
+          "Title": "Timing attack in OpenSSL"
+        }
+      ]
+    }
+  ]
+}

test/fixtures/target/cve-arm64.json

@@ -0,0 +1,22 @@
+{
+  "SchemaVersion": 2,
+  "ArtifactName": "debian:bullseye-slim",
+  "ArtifactType": "container_image",
+  "Results": [
+    {
+      "Target": "debian:bullseye-slim (debian 11)",
+      "Class": "os-pkgs",
+      "Type": "debian",
+      "Vulnerabilities": [
+        {
+          "VulnerabilityID": "CVE-2023-0001",
+          "PkgName": "glibc",
+          "InstalledVersion": "2.31-13+deb11u5",
+          "FixedVersion": "2.31-13+deb11u6",
+          "Severity": "CRITICAL",
+          "Title": "Memory corruption in glibc"
+        }
+      ]
+    }
+  ]
+}