patch-cve

name	patch-cve
description	Use this skill when the user asks to "patch a CVE", "fix a CVE", "handle a CVE", "check a CVE", or discusses Docker image vulnerabilities, docker scout findings, or Go/dependency CVE remediation in the Dockerfile.
version	0.1.0

Patching CVEs in the Docker Image

This skill provides the workflow for patching CVEs found in the HolmesGPT Docker image. It covers identifying the source, checking if upstream fixes exist, applying patches, and validating the fix.

Workflow Overview

1. Identify  →  2. Check upstream  →  3. Apply fix  →  4. Build  →  5. Validate  →  6. Cleanup

Step 1: Identify the CVE Source

Run docker scout cves on the current image to understand which package/binary introduces the CVE:

docker scout cves <image> 2>&1 | grep -B20 -A5 "CVE-XXXX-XXXXX"

Key info to extract:

• Affected package: e.g., stdlib 1.25.5 (Go standard library), a system package, or a Python dependency
• Affected range: e.g., >=1.25.0-0, <1.25.7
• Fixed version: e.g., 1.25.7
• Which binary: identify which binary in the image pulls in the vulnerable dependency

Step 2: Check if Upstream Fixes Exist

Before rebuilding from source, always check if a newer release of the affected tool already includes the fix.

For Go-based tools (ArgoCD, Helm, etc.)

1. Check the latest release version:

   curl -s https://api.github.com/repos/<org>/<repo>/releases/latest | python3 -c "import sys,json; print(json.load(sys.stdin)['tag_name'])"
   

2. Check Go version in that release — download the binary and inspect:

   # For tools that show version info with Go version
   ./<tool> version
   

   Or check go.mod in the release tag:

   curl -s https://raw.githubusercontent.com/<org>/<repo>/<tag>/go.mod | head -5
   

   Important: go.mod shows the minimum Go version, but the binary may be compiled with a newer Go toolchain. Always prefer checking the actual binary's version output.

3. Check upstream PRs/issues for the CVE — it may be merged to master but not yet in a release branch. Search:

   https://github.com/<org>/<repo>/pulls?q=CVE-XXXX-XXXXX
   

For system packages (apt)

Check if a newer version is available:

apt-get update && apt-cache policy <package>

For Python dependencies

Check if a newer version fixes the CVE:

pip index versions <package>

Step 3: Apply the Fix

Choose the appropriate strategy based on findings:

Strategy A: Upgrade to a fixed upstream release (preferred)

If a newer release includes the fix, simply update the version in the Dockerfile:

ARG TOOL_VERSION=vX.Y.Z  # Updated from vX.Y.W to fix CVE-XXXX-XXXXX

Strategy B: Rebuild from source with patched compiler/dependency

If upstream hasn't released a fix yet, rebuild the tool from source. For Go CVEs:

FROM golang:<fixed-version> AS go-builder
RUN git clone --depth 1 --branch <version> <repo> /build/<tool>
WORKDIR /build/<tool>
RUN CGO_ENABLED=0 go build -o /go/bin/<tool> <build-path>

Or use the pre-built binary approach (see Strategy C).

Strategy C: Pre-build binaries locally (fastest Docker builds)

For tools that are slow to compile, build locally for both architectures and commit to the repo:

1. Create a build script in scripts/ (see scripts/build_go_binaries.sh for reference)
2. Build for both linux/amd64 and linux/arm64 using cross-compilation:

   CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -o bin/<tool>/amd64/<tool> <build-path>
   CGO_ENABLED=0 GOOS=linux GOARCH=arm64 go build -o bin/<tool>/arm64/<tool> <build-path>
   

3. Use ARG TARGETARCH in Dockerfile to select the right binary:

   ARG TARGETARCH
   COPY bin/<tool>/${TARGETARCH}/<tool> /usr/local/bin/<tool>
   

4. Consider using Git LFS for large binaries (~200MB+)

Strategy D: Pin system package version

For apt packages:

RUN apt-get install -y <package>=<fixed-version>

Step 4: Build the Docker Image

Build for the target platform:

docker build --platform linux/amd64 -t holmes-cve-test:latest .

Note: For a quick validation, building for a single platform is sufficient. Multi-platform builds (linux/amd64,linux/arm64) can be done after the fix is confirmed.

Step 5: Validate the Fix

This is the most critical step. Never skip validation.

5a: Check the specific CVE is gone

docker scout cves holmes-cve-test:latest 2>&1 | grep -A5 "CVE-XXXX-XXXXX"

• If no output → CVE is fixed
• If still present → the fix didn't work, go back to Step 2

5b: Run a full scan and review remaining CVEs

docker scout cves holmes-cve-test:latest 2>&1 | grep -E "✗ (CRITICAL|HIGH)"

Check if the fix introduced any new vulnerabilities or if there are other CVEs that should be addressed.

5c: Verify the tool still works

docker run --rm holmes-cve-test:latest <tool> version
docker run --rm holmes-cve-test:latest <tool> --help

Step 6: Document and Clean Up

1. Add comments in the Dockerfile explaining the CVE patch and when it can be reverted:

   # Rebuilt with Go 1.25.7 to fix CVE-2025-68121.
   # Revert when <tool> releases a version built with Go >= 1.25.7.
   

2. Remove temporary workarounds when upstream releases a fix. Keep track of what needs reverting.

3. Clean up test images:

   docker rmi holmes-cve-test:latest
   

Common Patterns

Go stdlib CVEs

These are the most common. A CVE in Go's standard library affects every Go binary in the image. Steps:

1. Identify all Go binaries in the image and their Go versions
2. Check if newer releases of each tool use a fixed Go version
3. Only rebuild the ones that still use a vulnerable Go version

Multi-binary images

When the image contains multiple Go binaries (e.g., ArgoCD + Helm), each may use a different Go version. Check and fix each independently — don't assume fixing one fixes all.

Checklist

• Identified which binary/package introduces the CVE
• Checked latest upstream releases for a fix
• Checked upstream PRs/issues for pending fixes
• Applied the fix (upgrade or rebuild)
• Built the Docker image successfully
• Ran docker scout cves and confirmed the CVE is gone
• Verified the patched tool still works (--help, version)
• Added Dockerfile comments explaining the patch and revert conditions
• Confirmed both architectures are supported (amd64 + arm64)