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 GITHUBENV 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.