Socket.IO enables bidirectional and low-latency communication for every platform. Prior to 4.2.7, 3.4.5, and 3.3.6, a specially crafted Socket.IO packet can make the server wait for a large number of binary attachments and buffer them, which can be exploited to make the server run out of memory. This vulnerability is fixed in 4.2.7, 3.4.5, and 3.3.6.

Affected: npm: socket.io-parser

### Impact

A specially crafted Socket.IO packet can make the server wait for a large number of binary attachments and buffer them, which can be exploited to make the server run out of memory.

### Patches

| Version range | Used by | Fixed version | |------------------|--------------------------------------------|---------------| | `>=4.0.0 <4.2.7` | `socket.io@4.x` and `socket.io-client@4.x` | `4.2.7` | | `>=3.4.0 <3.4.5` | `socket.io@2.x` | `3.4.5` | | `<3.3.6` | `socket.io-client@2.x` | `3.3.6` |

### 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 a discussion [here](https://github.com/socketio/socket.io/discussions)

Affected: Ubuntu:18.04:LTS: node-socket.io-parser, Ubuntu:20.04:LTS: node-socket.io-parser, Ubuntu:22.04:LTS: node-socket.io-parser, Ubuntu:24.04:LTS: node-socket.io-parser, Ubuntu:26.04:LTS: node-socket.io-parser

Socket.IO enables bidirectional and low-latency communication for every platform. Prior to 4.2.7, 3.4.5, and 3.3.6, a specially crafted Socket.IO packet can make the server wait for a large number of binary attachments and buffer them, which can be exploited to make the server run out of memory. This vulnerability is fixed in 4.2.7, 3.4.5, and 3.3.6.