Uncaught Exception in engine.io

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 | | --- | --- | | engine.io@4.x.x | 4.1.2 | | engine.io@5.x.x | 5.2.1 | | engine.io@6.x.x | 6.1.1 |

Previous versions (< 4.0.0) are not impacted.

For socket.io users:

| Version range | engine.io version | Needs minor update? | | --- | --- | --- | | socket.io@4.4.x | ~6.1.0 | - | socket.io@4.3.x | ~6.0.0 | Please upgrade to socket.io@4.4.x | socket.io@4.2.x | ~5.2.0 | - | socket.io@4.1.x | ~5.1.1 | Please upgrade to socket.io@4.4.x | socket.io@4.0.x | ~5.0.0 | Please upgrade to socket.io@4.4.x | socket.io@3.1.x | ~4.1.0 | - | socket.io@3.0.x | ~4.0.0 | Please upgrade to socket.io@3.1.x or socket.io@4.4.x (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.