EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
engine.io📦engine.io📦engine.ioReal-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
Impact
A specially crafted HTTP request can trigger an uncaught exception on the Engine.IO server, thus killing the Node.js process.
RangeError: Invalid WebSocket frame: RSV2 and RSV3 must be clear at Receiver.getInfo (/.../node_modules/ws/lib/receiver.js:176:14) at Receiver.startLoop (/.../node_modules/ws/lib/receiver.js:136:22) at Receiver._write (/.../node_modules/ws/lib/receiver.js:83:10) at writeOrBuffer (internal/streams/writable.js:358:12)
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.
Patches
A fix has been released for each major branch:
| Version range | Fixed version |
|---|---|
[email protected] | 4.1.2 |
[email protected] | 5.2.1 |
[email protected] | 6.1.1 |
Previous versions (< 4.0.0) are not impacted.
For socket.io users:
| Version range | engine.io version | Needs minor update? |
|---|---|---|
[email protected] | ~6.1.0 | - |
[email protected] | ~6.0.0 | Please upgrade to [email protected] |
[email protected] | ~5.2.0 | - |
[email protected] | ~5.1.1 | Please upgrade to [email protected] |
[email protected] | ~5.0.0 | Please upgrade to [email protected] |
[email protected] | ~4.1.0 | - |
[email protected] | ~4.0.0 | Please upgrade to [email protected] or [email protected] (see here) |
In most cases, running npm audit fix should be sufficient. You can also use npm update engine.io --depth=9999.
Workarounds
There is no known workaround except upgrading to a safe version.
For more information
If you have any questions or comments about this advisory:
- Open an issue in
engine.io
Thanks to Marcus Wejderot from Mevisio for the responsible disclosure.
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 GHSA-273r-mgr4-v34f 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-273r-mgr4-v34f 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-273r-mgr4-v34f. 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-273r-mgr4-v34f in your dependencies?
O3 detects GHSA-273r-mgr4-v34f across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.