CVE-2023-27581
HIGHCVE-2023-27581 is a high-severity (CVSS 8.8) CWE-77 vulnerability in rlespinasse/github-slug-action. 1 public exploit reference exists, so weaponization risk is real. O3 Security confirms whether CVE-2023-27581 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
github-slug-action vulnerable to arbitrary code execution
Blast Radius
rlespinasse/github-slug-actionReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects GitHub Actions packages — download data is not available via public APIs for these ecosystems.
Description
github-slug-action is a GitHub Action to expose slug value of GitHub environment variables inside of one's GitHub workflow. Starting in version 4.0.0and prior to version 4.4.1, this action uses thegithub.head_ref` parameter in an insecure way. This vulnerability can be triggered by any user on GitHub on any workflow using the action on pull requests. They just need to create a pull request with a branch name, which can contain the attack payload. This can be used to execute code on the GitHub runners and to exfiltrate any secrets one uses in the CI pipeline. A patched action is available in version 4.4.1. No workaround is available.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦GitHub Actions | rlespinasse/github-slug-action | ≥ 4.0.0&&< 4.4.1 | 4.4.1 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for rlespinasse/github-slug-action. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update rlespinasse/github-slug-action to 4.4.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-27581 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2023-27581 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2023-27581. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2023-27581 in your dependencies?
O3 detects CVE-2023-27581 across GitHub Actions dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.