GHSA-4r4m-hjwj-43p8 is a medium-severity (CVSS 5.9) CWE-300 vulnerability in engine.io-client. O3 Security confirms whether GHSA-4r4m-hjwj-43p8 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Insecure Defaults Allow MITM Over TLS in engine.io-client
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.
engine.io-clientnpmDescription
Affected versions of engine.io-client do not verify certificates by default, and as such may be vulnerable to Man-in-the-Middle attacks.
The vulnerability is related to the way that node.js handles the rejectUnauthorized setting. If the value is something that evaluates to false, such as undefined or null, certificate verification will be disabled.
Recommendation
Update to version 1.6.9 or later.
If you are unable to upgrade, ensure all calls to socket.io to have a rejectedUnauthorized: true flag.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | engine.io-client | all versions | 1.6.9 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for engine.io-client. 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 engine.io-client to 1.6.9 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-4r4m-hjwj-43p8 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-4r4m-hjwj-43p8 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-4r4m-hjwj-43p8. 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-4r4m-hjwj-43p8 in your dependencies?
O3 detects GHSA-4r4m-hjwj-43p8 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.