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".