CVE-2022-21676
HIGHCVE-2022-21676 is a high-severity (CVSS 7.5) CWE-754 vulnerability in engine.io. O3 Security confirms whether CVE-2022-21676 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Uncaught Exception in engine.io
Blast Radius
Weekly download volume for affected packages — a proxy for how broadly this vulnerability is deployed.
engine.ionpmDescription
Engine.IO is the implementation of transport-based cross-browser/cross-device bi-directional communication layer for Socket.IO. A specially crafted HTTP request can trigger an uncaught exception on the Engine.IO server, thus killing the Node.js process. This impacts all the users of the engine.io package starting from version 4.0.0, including those who uses depending packages like socket.io. Versions prior to 4.0.0 are not impacted. A fix has been released for each major branch, namely 4.1.2 for the 4.x.x branch, 5.2.1 for the 5.x.x branch, and 6.1.1 for the 6.x.x branch. There is no known workaround except upgrading to a safe version.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | engine.io | ≥ 4.0.0&&< 4.1.2 | 4.1.2 |
| 📦npm | engine.io | ≥ 5.0.0&&< 5.2.1 | 5.2.1 |
| 📦npm | engine.io | ≥ 6.0.0&&< 6.1.1 | 6.1.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for engine.io. 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 to 4.1.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2022-21676 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 CVE-2022-21676 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 CVE-2022-21676. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2022-21676 in your dependencies?
O3 detects CVE-2022-21676 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.