CVE-2026-33151
socket.io allows an unbounded number of binary attachments
Impact
### 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 If you have any questions or comments about this advisory: - Open a discussion [here](https://github.com/socketio/socket.io/discussions)
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| npm | socket.io-parser | < 3.3.5 | 3.3.5 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Socket | Socket.Io-Parser | before 3.3.5 from 3.4.0 before 3.4.4 from 4.0.0 before 4.2.6 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/socketio/socket.io/commit/719f9ebab0772ffb882bd614b387e585c1aa75d4
- https://github.com/socketio/socket.io/commit/9d39f1f080510f036782f2177fac701cc041faaf
- https://github.com/socketio/socket.io/commit/b25738c416c4e32fbff62ee182afa8f6d0dacf78
- https://github.com/socketio/socket.io/security/advisories/GHSA-677m-j7p3-52f9
- https://github.com/advisories/GHSA-677m-j7p3-52f9
- https://nvd.nist.gov/vuln/detail/CVE-2026-33151