Medium (5.0) in github toolkit. EPSS 0.7% chance of exploitation in the next 30 days. Fixed in @actions/core 1.9.1.
The GitHub Actions ToolKit provides a set of packages to make creating actions easier. 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. Users should upgrade to `@actions/core v1.9.1`. 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`.
Severity
CVSS 3.1
5.0 medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:L/A:N
EPSS
0.7% chance of exploitation in the next 30 days; higher than 53% of CVEs (scores of 2026-10-31)