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 <4.2.6 | socket.io@4.x and socket.io-client@4.x | 4.2.6 | | >=3.4.0 <3.4.4 | socket.io@2.x | 3.4.4 | | <3.3.5 | socket.io-client@2.x | 3.3.5 |

Workarounds

There is no known workaround except upgrading to a safe version.

For more information

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Due to improper type validation in attachment parsing the Socket.io js library, it is possible to overwrite the placeholder object which allows an attacker to place references to functions at arbitrary places in the resulting query object.