CVE-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…

PriorityP346high7.5CVSS 3.1

AVNACLPRNUINSUCNINAH

EPSS

0.87%

54.7th percentile

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

vendor_debian7.5HIGH

vendor_redhat7.5HIGH

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