Actions expression injection in `filter-test-configs` (`GHSL-2023-181`)
Date: 2023-08
Affected: actions/https://github.com/pytorch/pytorch/.github/actions/filter-test-configs
Attack vector: path-traversal
Category: vulnerability-disclosure
Severity: Medium

The `pytorch/pytorch` `filter-test-configs` workflow is vulnerable to an expression injection in Actions, allowing an attacker to potentially leak secrets and alter the repository using the workflow. ### Details The [`filter-test-configs`](https://github.com/pytorch/pytorch/blob/ec26947c586dd323d741da80008403664c533f65/.github/actions/filter-test-configs/action.yml) workflow is using the raw `github.event.workflow_run.head_branch` value inside the `filter` step: ```yaml - name: Select all requested test configurations shell: bash env: GITHUB_TOKEN: ${{ inputs.github-token }} JOB_NAME: ${{ steps.get-job-name.outputs.job-name }} id: filter run: | ... python3 "${GITHUB_ACTION_PATH}/../../scripts/filter_test_configs.py" \ ... --branch "${{ github.event.workflow_run.head_branch }}" ``` In the event of a repository using `filter-test-configs` in a `pull_request_target`-triggered workflow, an attacker could use a malicious branch name to gain command execution in the step and potentially leak secrets. ```yml name: Example on: pull_request_target jobs: example: runs-on: ubuntu-latest steps: - name: Filter uses: pytorch/pytorch/.github/actions/filter-test-configs@v2 ``` #### Impact This issue may lead to stealing workflow secrets. #### Remediation 1. Use an intermediate environment variable for potentially attacker-controlled values such as `github.event.workflow_run.head_branch`: ```yaml - name: Select all request


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Architectural layers (MAESTRO):