CVE-2025-66219 — willitmerge
CVE-2025-66219 is a CWE-77 vulnerability in willitmerge. The records list no fixed version yet; check the vendor advisory below and apply the mitigations in the meantime.
willitmerge has a Command Injection vulnerability
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
Exploitation and automatability from CISA’s SSVC triage for CVE-2025-66219.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
willitmergenpmDescription
willitmerge describes itself as a command line tool to check if pull requests are mergeable. There is a Command Injection vulnerability in version [email protected].
Resources:
- Project's GitHub source code: https://github.com/shama/willitmerge/
- Project's npm package: https://www.npmjs.com/package/willitmerge
Background on exploitation
Reporting a Command Injection vulnerability in willitmerge npm package.
A security vulnerability manifests in this package due to the use of insecure child process execution API (exec) to which it concateanes user input, whether provided to the command-line flag, or is in user control in the target repository.
Exploit
POC 1
- Install
willitmerge - Run it with the following command
willitmerge --verbose --remote "https://github.com/lirantal/npq.git; touch /tmp/hel"
- Confirm the file
/tmp/helis created on disk
GitHub-sourced attack vector
Lines 189-197 in lib/willitmerge.js
pass user input controlled by repository collaborators into the git command:
var cmds = [
'git checkout -b ' + branch + ' ' + that.options.remote + '/' + iss.base.ref,
'git remote add ' + branch + ' ' + gitUrl,
'git pull ' + branch + ' ' + iss.head.ref,
'git reset --merge HEAD',
'git checkout ' + origBranch,
'git branch -D ' + branch,
'git remote rm ' + branch
];
Users creating malicious branch names such as ;{echo,hello,world}>/tmp/c
This is a similar attack vector to that which was reported for the [pullit vulnerability (https://security.snyk.io/vuln/npm:pullit:20180214)
Author
Liran Tal
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | willitmerge | all versions | No fix |
Affected Products
willitmergedontkryDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for willitmerge, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Remediation status
The records we use list no patched version of willitmerge for CVE-2025-66219. Check the maintainer's advisory, and where your build allows, override or pin the dependency away from the vulnerable range.
Mitigate without a patch
Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.
Frequently Asked Questions
Is CVE-2025-66219 in your dependencies?
Find it across npm, including transitive dependencies.