gha-security-review

GitHub Actions Security Review

Find exploitable vulnerabilities in GitHub Actions workflows. Every finding MUST include a concrete exploitation scenario — if you can't build the attack, don't report it.

This skill encodes attack patterns from real GitHub Actions exploits — not generic CI/CD theory.

When to Use

• You are reviewing GitHub Actions workflows for exploitable security issues.
• The task requires tracing a concrete attack path from an external attacker to workflow execution or secret exposure.
• You need a security review of workflow files, composite actions, or workflow-related scripts with evidence-based findings only.

Scope

Review the workflows provided (file, diff, or repo). Research the codebase as needed to trace complete attack paths before reporting.

Files to Review

• .github/workflows/*.yml — all workflow definitions
• action.yml / action.yaml — composite actions in the repo
• .github/actions/*/action.yml — local reusable actions
• Config files loaded by workflows: CLAUDE.md, AGENTS.md, Makefile, shell scripts under .github/

Out of Scope

• Workflows in other repositories (only note the dependency)
• GitHub App installation permissions (note if relevant)

Threat Model

Only report vulnerabilities exploitable by an external attacker — someone without write access to the repository. The attacker can open PRs from forks, create issues, and post comments. They cannot push to branches, trigger workflow_dispatch, or trigger manual workflows.

Do not flag vulnerabilities that require write access to exploit:

• workflow_dispatch input injection — requires write access to trigger
• Expression injection in push-only workflows on protected branches
• workflow_call input injection where all callers are internal
• Secrets in workflow_dispatch/schedule-only workflows