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Security rules for GitHub Actions workflow files

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Rules (3)

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Using variable interpolation `${{...}}` with `github` context data in a `run:` step could allow an attacker to inject their own code into the runner. This would allow them to steal secrets and code. `github` context data can have arbitrary user input and should be treated as untrusted. Instead, use an intermediate environment variable with `env:` to store the data and use the environment variable in the `run:` script. Be sure to use double-quotes the environment variable, like this: "$ENVVAR".

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This GitHub Actions workflow file uses `pull_request_target` and checks out code from the incoming pull request. When using `pull_request_target`, the Action runs in the context of the target repository, which includes access to all repository secrets. Normally, this is safe because the Action only runs code from the target repository, not the incoming PR. However, by checking out the incoming PR code, you're now using the incoming code for the rest of the action. You may be inadvertently executing arbitrary code from the incoming PR with access to repository secrets, which would let an attacker steal repository secrets. This normally happens by running build scripts (e.g., `npm build` and `make`) or dependency installation scripts (e.g., `python install`). Audit your workflow file to make sure no code from the incoming PR is executed. Please see for additional mitigations.

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The environment variable `ACTIONS_ALLOW_UNSECURE_COMMANDS` grants this workflow permissions to use the `set-env` and `add-path` commands. There is a vulnerability in these commands that could result in environment variables being modified by an attacker. Depending on the use of the environment variable, this could enable an attacker to, at worst, modify the system path to run a different command than intended, resulting in arbitrary code execution. This could result in stolen code or secrets. Don't use `ACTIONS_ALLOW_UNSECURE_COMMANDS`. Instead, use Environment Files. See for more information.