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Security Advisories: GSA_kwCzR0hTQS1tY3BoLW0yNWotOGo2M84AA4Jm

tj-actions/changed-files has Potential Actions command injection in output filenames (GHSL-2023-271)


The tj-actions/changed-files workflow allows for command injection in changed filenames, allowing an attacker to execute arbitrary code and potentially leak secrets.


The changed-files action returns a list of files changed in a commit or pull request which provides an escape_json input enabled by default, only escapes " for JSON values.

This 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 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.

Proof of Concept

  1. Submit a pull request to a repository with a new file injecting a command. For example $(whoami).txt which is a valid filename.
  2. 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 step below.
      - name: List all changed files
        run: |
          for file in ${{ steps.changed-files.outputs.all_changed_files }}; do
            echo "$file was changed"

Example output:

##[group]Run for file in $(whoami).txt; do
    for file in $(whoami).txt; do
        echo "$file was changed"
shell: /usr/bin/bash -e {0}
runner.txt was changed


This issue may lead to arbitrary command execution in the GitHub Runner.


- name: List all changed files
    ALL_CHANGED_FILES: ${{ steps.changed-files.outputs.all_changed_files }}
  run: |
    for file in "$ALL_CHANGED_FILES"; do
      echo "$file was changed"


Source: GitHub Advisory Database
Origin: Unspecified
Severity: High
Classification: General
Published: 4 months ago
Updated: 4 months ago

CVSS Score: 7.3
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N

Identifiers: GHSA-mcph-m25j-8j63, CVE-2023-51664
References: Repository:
Blast Radius: 1.0

Affected Packages

Affected Version Ranges: < 41
Fixed in: 41