GHSA-4g77-cvgw-grvw is a high-severity (CVSS 8.2) CWE-1321 vulnerability in putil-merge. 1 public exploit reference exists, so weaponization risk is real. O3 Security confirms whether GHSA-4g77-cvgw-grvw is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Prototype Pollution in putil-merge
Real-World Exposure
putil-mergeReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.
Description
This affects the package putil-merge before 3.8.0. The merge() function does not check the values passed into the argument. An attacker can supply a malicious value by adjusting the value to include the constructor property. Note: This vulnerability derives from an incomplete fix in https://security.snyk.io/vuln/SNYK-JS-PUTILMERGE-1317077
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | putil-merge | all versions | 3.8.0 |
Research 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 putil-merge. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update putil-merge to 3.8.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-4g77-cvgw-grvw 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.
How O3 protects you
O3 pinpoints whether GHSA-4g77-cvgw-grvw is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-4g77-cvgw-grvw. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-4g77-cvgw-grvw in your dependencies?
O3 detects GHSA-4g77-cvgw-grvw across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.