Improper Validation of Specified Quantity in Input in undici - CVE-2026-2229
Published: April 24, 2026
Vulnerability identifier: #VU127578
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-2229
CWE-ID: CWE-1284
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Node.js
Affected software:
undici
undici
Detailed vulnerability description
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to improper validation of specified quantity in WebSocket client permessage-deflate handling when processing a server response containing an out-of-range server_max_window_bits value followed by a compressed frame. A remote attacker can send a crafted WebSocket handshake response and compressed frame to cause a denial of service.
The issue results in an uncaught synchronous RangeError exception that terminates the Node.js process.
How to mitigate CVE-2026-2229
Install security update from vendor's website.