GHSA-c4w7-xm78-47vh is a high-severity (CVSS 7.3) CWE-1321 vulnerability in y18n. 3 public exploit references exist, so weaponization risk is real. O3 Security confirms whether GHSA-c4w7-xm78-47vh is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Prototype Pollution in y18n
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.
y18nnpmDescription
Overview
The npm package y18n before versions 3.2.2, 4.0.1, and 5.0.5 is vulnerable to Prototype Pollution.
POC
const y18n = require('y18n')();
y18n.setLocale('__proto__');
y18n.updateLocale({polluted: true});
console.log(polluted); // true
Recommendation
Upgrade to version 3.2.2, 4.0.1, 5.0.5 or later.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | y18n | all versions | 3.2.2 |
| 📦npm | y18n | ≥ 4.0.0&&< 4.0.1 | 4.0.1 |
| 📦npm | y18n | ≥ 5.0.0&&< 5.0.5 | 5.0.5 |
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 y18n. 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 y18n to 3.2.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-c4w7-xm78-47vh 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-c4w7-xm78-47vh 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-c4w7-xm78-47vh. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
In OpenShift Container Platform (OCP), OpenShift ServiceMesh (OSSM) and OpenShift distributed tracing the affected components are behind OpenShift OAuth authentication. This restricts access to the vulnerable nodejs-y18n library to authenticated users only, therefore the impact is Low. In Red Hat OpenShift Container…
Frequently Asked Questions
Is GHSA-c4w7-xm78-47vh in your dependencies?
O3 detects GHSA-c4w7-xm78-47vh across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.