{"id":"CVE-2023-52137","aliases":["GHSA-ghm2-rq8q-wrhc"],"url":"https://o3.security/vulnerability/CVE-2023-52137","summary":"GitHub Action tj-actions/verify-changed-files is vulnerable to command injection in output filenames","details":"### Summary\nThe [`tj-actions/verify-changed-files`](https://github.com/tj-actions/verify-changed-files) action allows for command injection in changed filenames, allowing an attacker to execute arbitrary code and potentially leak secrets.\n\n### Details\nThe [`verify-changed-files`](https://github.com/tj-actions/verify-changed-files) workflow returns the list of files changed within a workflow execution.\n\nThis could potentially allow filenames that contain special characters such as `;` and \\` (backtick) which can be used by an attacker to take over the [GitHub Runner](https://docs.github.com/en/actions/using-github-hosted-runners/about-github-hosted-runners) if the output value is used in a raw fashion (thus being directly replaced before execution) inside a `run` block. By running custom commands an attacker may be able to steal **secrets** such as `GITHUB_TOKEN` if triggered on other events than `pull_request`. For example on `push`.\n\n#### Proof of Concept\n\n1. Submit a pull request to the repository with a new file injecting a command. For example `$(whoami).txt` would be a valid filename.\n2. Upon approval of the workflow (triggered by the pull request), the action will get executed and the malicious pull request filename will flow into the `List all changed files tracked and untracked files` step.\n\n```yaml\n- name: List all changed files tracked and untracked files\n  run: |\n    echo \"Changed files: ${{ steps.verify-changed-files.outputs.changed_files }}\"\n```\n\nExample output:\n\n```yaml\n##[group]Run echo \"Changed files: $(whoami).txt\"\n  echo \"Changed files: $(whoami).txt\"\u001b[0m\nshell: /usr/bin/bash -e {0}\n##[endgroup]\nChanged files: runner.txt\n```\n\n### Impact\nThis issue may lead to arbitrary command execution in the GitHub Runner.\n\n### Resolution\n- A new `safe_output` input would be enabled by default and return filename paths escaping special characters like ;, ` (backtick), $, (), etc for bash environments.\n\n- A safe recommendation of using environment variables to store unsafe outputs.\n\n```yaml\n- name: List all changed files tracked and untracked files\n  env:\n     CHANGED_FILES: ${{ steps.verify-changed-files.outputs.changed_files }}\n  run: |\n    echo \"Changed files: $CHANGED_FILES\"\n```\n\n\n### Resources\n\n* [Keeping your GitHub Actions and workflows secure Part 2: Untrusted input](https://securitylab.github.com/research/github-actions-untrusted-input/)\n* [Keeping your GitHub Actions and workflows secure Part 1: Preventing pwn requests](https://securitylab.github.com/research/github-actions-preventing-pwn-requests/)\n","published":"2023-12-29T17:08:49.356Z","modified":"2026-10-28T02:31:09.492051378Z","cvss":{"score":7.7,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:L"},"epss":null,"cisaKev":null,"exploitsKnown":1,"affectedPackages":[{"ecosystem":"GitHub Actions","name":"tj-actions/verify-changed-files","fixedVersion":"17"}],"fix":{"url":"https://github.com/tj-actions/verify-changed-files/commit/498d3f316f501aa72485060e8c96fde7b2014f12","label":"tj-actions/verify-changed-files@498d3f3"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/52xxx/CVE-2023-52137.json"},{"type":"ADVISORY","url":"https://github.com/tj-actions/verify-changed-files/security/advisories/GHSA-ghm2-rq8q-wrhc"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2023-52137"},{"type":"FIX","url":"https://github.com/tj-actions/verify-changed-files/commit/498d3f316f501aa72485060e8c96fde7b2014f12"},{"type":"FIX","url":"https://github.com/tj-actions/verify-changed-files/commit/592e305da041c09a009afa4a43c97d889bed65c3"},{"type":"PACKAGE","url":"https://github.com/tj-actions/verify-changed-files"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-28T02:31:09.492051378Z"}}