CVE-2020-15228

Environment Variable Injection in GitHub Actions

Workarounds

None, it is strongly suggested that you upgrade as soon as possible.

For more information

If you have any questions or comments about this advisory:

• Open an issue in Actions Toolkit

The @actions/core npm module addPath and exportVariable functions communicate with the Actions Runner over stdout by generating a string in a specific format. Workflows that log untrusted data to stdout may invoke these commands, resulting in the path or environment variables being modified without the intention of the workflow or action author.

The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths. Typical impact: varies by context: data corruption, logic bypass, or denial of service.

CVE-2020-15228 has a CVSS score of 3.5 (Low). 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 (1.2.6); upgrading removes the vulnerable code path.

Kodem intelligence

Already deployed Kodem?

The runner will release an update that disables the set-env and add-path workflow commands in the near future. For now, users should upgrade to @actions/core v1.2.6 or later, and replace any instance of the set-env or add-path commands in their workflows with the new Environment File Syntax. Workflows and actions using the old commands or older versions of the toolkit will start to warn, then error out during workflow execution.

1. What is CVE-2020-15228? CVE-2020-15228 is a low-severity improper input validation vulnerability in @actions/core (npm), affecting versions < 1.2.6. It is fixed in 1.2.6. The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths.
2. How severe is CVE-2020-15228? CVE-2020-15228 has a CVSS score of 3.5 (Low). 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 @actions/core are affected by CVE-2020-15228? @actions/core (npm) versions < 1.2.6 is affected.
4. Is there a fix for CVE-2020-15228? Yes. CVE-2020-15228 is fixed in 1.2.6. Upgrade to this version or later.
5. Is CVE-2020-15228 exploitable, and should I be worried? Whether CVE-2020-15228 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-2020-15228 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-2020-15228? Upgrade @actions/core to 1.2.6 or later.

Other vulnerabilities in @actions/core