CI/CD pipelines are one of the highest-leverage attack surfaces in the application supply chain. A single misconfigured GitHub Actions workflow can hand repository secrets and write tokens to any external contributor who opens a pull request.

This talk presents a methodology for finding these weaknesses at scale across open-source organizations. It covers four vulnerability classes: unpinned third-party actions (the CVE-2025-30066 pattern), pwn-request code execution via pull_request_target, excessive GITHUB_TOKEN scope, and expression injection into shell steps.

Two open-source scanners implement the methodology. One audits SHA-pinning across a GitHub org. The other does mitigation-aware triage: it detects when hardening like persist-credentials: false or insider-only gating neutralizes a finding, so output stays actionable rather than noisy.

The talk walks through real disclosed findings, including a CRITICAL-severity pwn request where a pull_request_target workflow executed attacker-controlled build scripts with secrets in scope. Attendees leave with two working scanners, a triage framework for separating real findings from false positives, and concrete fix patterns they can apply to their own organizations.

Validation at scale: the methodology behind this talk has produced over 320 merged security fixes across 75 open-source organizations (apache, google, kubernetes-sigs, containerd, prometheus, vuejs, eslint, mongodb, ruby, redis, OWASP, NASA, NIST), plus five private vulnerability disclosures including a CRITICAL-severity pwn request. Each merged PR represents an independent maintainer reviewing and accepting a scanner-identified fix.