HighGHSA-677m-j7p3-52f9CVE-2026-33151

socket.io allows an unbounded number of binary attachments

Published 18 Mar 2026 · Updated 10 Sept 2026

Affected packages

socket.io-parsernpm
Affected
<3.3.5
Fixed in
3.3.5
Update to the fixed version for your release line, for example:npm install socket.io-parser@3.3.5
socket.io-parsernpm
Affected
>=3.4.0 <3.4.4
Fixed in
3.4.4
Update to the fixed version for your release line, for example:npm install socket.io-parser@3.4.4
socket.io-parsernpm
Affected
>=4.0.0 <4.2.6
Fixed in
4.2.6
Update to the fixed version for your release line, for example:npm install socket.io-parser@4.2.6

Details

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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References

Advisory data from OSV.dev (opens OSV.dev in a new tab), refreshed daily.