@actions/core has Delimiter Injection Vulnerability in exportVariable

Impact

The core.exportVariable function uses a well known delimiter that attackers can use to break out of that specific variable and assign values to other arbitrary variables. Workflows that write untrusted values to the GITHUB_ENV file may cause the path or other environment variables to be modified without the intention of the workflow or action author.

Patches

Users should upgrade to @actions/core v1.9.1.

Workarounds

If you are unable to upgrade the @actions/core package, you can modify your action to ensure that any user input does not contain the delimiter _GitHubActionsFileCommandDelimeter_ before calling core.exportVariable.

References

More information about setting-an-environment-variable in workflows

If you have any questions or comments about this advisory:

• Open an issue in actions/toolkit