YAML Anchors Exposed Blind Spots in GitHub Workflow Scanning
zizmor’s old anchor handling did more than miss a corner case. It created analyzer blind spots in valid GitHub Actions workflows, so a clean scan could still leave pull_request_target misconfigurations untested. That matters because the recent Trivy supply-chain exploit showed how those workflow mistakes turn into secret theft and downstream compromise.
Trail of Bits and the zizmor maintainers added full YAML anchor support, fixed parsing and deserialization bugs, and aligned the expression evaluator with GitHub’s tests. They validated the changes against 41,253 real workflows from 6,612 high-value repositories, and the work closed crashes and wrong-location findings that affected anchor-using files.