VULNERABILITY INTELLIGENCE

CVE-2026-2229

CVSS score7.5 HIGH
EPSS probability0.91%
CISA KEVNot currently listed
Published2026-03-12
Last modified2026-09-04
CVSS vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Description

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

Weakness classification

  • ce714d77-add3-4f53-aff5-83d477b104bb: CWE-248
  • 0b0ca135-0b70-47e7-9f44-1890c2a1c46c: CWE-248

Primary references