CVE-2023-27581

github-slug-action vulnerable to arbitrary code execution

Workarounds

No workaround is available if impacted, please upgrade the version

ℹ️ v3 and v4 are compatibles.

References

Here is a set of blog posts by Github's security team explaining this issue.

Thanks

Thanks to the team of researchers from Purdue University, who are working on finding vulnerabilities in CI/CD configurations of open-source software. Their tool detected this security vulnerability.

This action uses the github.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. (Note that first-time PR requests will not be run - but the attacker can submit a valid PR before submitting an invalid PR). This can be used to execute code on the GitHub runners (potentially use it for crypto-mining, and waste your resources) and to exfiltrate any secrets you use in the CI pipeline.

Untrusted input is inserted into a command that is later executed by the application, allowing the attacker to alter the intent of that command. Typical impact: arbitrary command execution in the application's environment.

CVE-2023-27581 has a CVSS score of 8.8 (High). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (4.4.1); upgrading removes the vulnerable code path.

Kodem intelligence

Already deployed Kodem?

Pass the variable as an environment variable and then use the environment variable instead of substituting it directly.

Patched action is available on tag v4, tag v4.4.1, and any tag beyond.

1. What is CVE-2023-27581? CVE-2023-27581 is a high-severity command injection vulnerability in rlespinasse/github-slug-action (actions), affecting versions >= 4.0.0, < 4.4.1. It is fixed in 4.4.1. Untrusted input is inserted into a command that is later executed by the application, allowing the attacker to alter the intent of that command.
2. How severe is CVE-2023-27581? CVE-2023-27581 has a CVSS score of 8.8 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of rlespinasse/github-slug-action are affected by CVE-2023-27581? rlespinasse/github-slug-action (actions) versions >= 4.0.0, < 4.4.1 is affected.
4. Is there a fix for CVE-2023-27581? Yes. CVE-2023-27581 is fixed in 4.4.1. Upgrade to this version or later.
5. Is CVE-2023-27581 exploitable, and should I be worried? Whether CVE-2023-27581 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2023-27581 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2023-27581? Upgrade rlespinasse/github-slug-action to 4.4.1 or later.

Other vulnerabilities in rlespinasse/github-slug-action