CVE-2026-2229
published 2026-03-12CVE-2026-2229: ImpactThe undici WebSocket client is vulnerable to a denial-of-service attack due to improper validation of the server_max_window_bits parameter in the…
high7.5CVSS 3.1
AVNACLPRNUINSUCNINAH
ImpactThe undici WebSocket client is vulnerable to a denial-of-service attack due to improper validation of the server_max_window_bits parameter in the permessage-deflate extension. When a WebSocket client connects to a server, it automatically advertises support for permessage-deflate compression. A malicious server can respond with an out-of-range server_max_window_bits value (outside zlib's valid range of 8-15). When the server subsequently sends a compressed frame, the client attempts to create a zlib InflateRaw instance with the invalid windowBits value, causing a synchronous RangeError exception that is not caught, resulting in immediate process termination.
The vulnerability exists because:
* The isValidClientWindowBits() function only validates that the value contains ASCII digits, not that it falls within the valid range 8-15
* The createInflateRaw() call is not wrapped in a try-catch block
* The resulting exception propagates up through the call stack and crashes the Node.js process
Affected
6 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| debian | node-undici | < node-undici 7.24.5+dfsg+~cs3.2.0-1 (forky) | node-undici 7.24.5+dfsg+~cs3.2.0-1 (forky) |
| nodejs | undici | < 6.24.0 | 6.24.0 |
| nodejs | undici | >= 7.0.0 < 7.24.0 | 7.24.0 |
| undici | undici | < 6.24.0; 7.0.0 < 7.24.0 | 6.24.0; 7.0.0 < 7.24.0 |
| undici | undici | >= 0 < 6.24.0 | 6.24.0 |
| undici | undici | >= 7.0.0 < 7.24.0 | 7.24.0 |
CVSS provenance
nvdv3.17.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
osv7.5HIGH