CVE-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. A fix is available for rlespinasse/github-slug-action — see the affected versions and patch details below.
github-slug-action vulnerable to arbitrary code execution
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2023-27581.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2023-27581 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,166 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2023-27581 can be triaged on real exposure rather than presence alone.
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 Security finds CVE-2023-27581 across GitHub Actions dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.