CVE-2024-38355: Unhandled 'error' event in socket.io

Impact

A specially crafted Socket.IO packet can trigger an uncaught exception on the Socket.IO server, thus killing the Node.js process.

node:events:502 throw err; // Unhandled 'error' event ^

Error [ERRUNHANDLEDERROR]: Unhandled error. (undefined) at new NodeError (node:internal/errors:405:5) at Socket.emit (node:events:500:17) at /myapp/nodemodules/socket.io/lib/socket.js:531:14 at process.processTicksAndRejections (node:internal/process/taskqueues:77:11) { code: 'ERRUNHANDLEDERROR', context: undefined }

Affected versions

| Version range | Needs minor update? | |------------------|------------------------------------------------| | 4.6.2...latest | Nothing to do | | 3.0.0...4.6.1 | Please upgrade to socket.io@4.6.2 (at least) | | 2.3.0...2.5.0 | Please upgrade to socket.io@2.5.1 |

Patches

This issue is fixed by https://github.com/socketio/socket.io/commit/15af22fc22bc6030fcead322c106f07640336115, included in socket.io@4.6.2 (released in May 2023).

The fix was backported in the 2.x branch today: https://github.com/socketio/socket.io/commit/d30630ba10562bf987f4d2b42440fc41a828119c

Workarounds

As a workaround for the affected versions of the socket.io package, you can attach a listener for the "error" event:

js io.on("connection", (socket) => { socket.on("error", () => { // ... }); });

For more information

If you have any questions or comments about this advisory:

- Open a discussion here

Thanks a lot to Paul Taylor for the responsible disclosure.

References

- https://github.com/socketio/socket.io/commit/15af22fc22bc6030fcead322c106f07640336115 - https://github.com/socketio/socket.io/commit/d30630ba10562bf987f4d2b42440fc41a828119c