What is the CVSS score of CVE-2026-2229?

CVE-2026-2229 has a CVSS 3.1 base score of 7.5 (High). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. EPSS exploitation probability: 0.1%.

Which versions of Node.js are affected by CVE-2026-2229?

A high-severity denial-of-service vulnerability (CVE-2026-2229) affects the undici WebSocket client library, allowing attackers to crash applications that use WebSocket connections.. A patch is available.

How to fix or mitigate CVE-2026-2229?

Within 24 hours: Identify all systems and applications using the undici WebSocket client and assess their criticality and exposure. Within 7 days: Implement compensating controls including WebSocket traffic filtering at the perimeter and disable permessage-deflate compression if operationally feasible. Within 30 days: Develop and test a patching strategy; monitor the vendor's security advisories for patch availability and plan immediate deployment upon release.

Node.js CVE-2026-2229

EUVD-2026-11704 HIGH

Uncaught Exception (CWE-248)

2026-03-12 ce714d77-add3-4f53-aff5-83d477b104bb

GHSA-v9p9-hfj2-hcw8

Node.js Denial Of Service Undici

7.5

CVSS 3.1 · Vendor: ce714d77-add3-4f53-aff5-83d477b104bb

Severity by source

Vendor (ce714d77-add3-4f53-aff5-83d477b104bb) PRIMARY

7.5 HIGH

AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

SUSE

HIGH

qualitative

Red Hat

7.5 HIGH

qualitative

Primary rating from Vendor (ce714d77-add3-4f53-aff5-83d477b104bb).

CVSS VectorVendor: ce714d77-add3-4f53-aff5-83d477b104bb

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Lifecycle Timeline

Patch released

Mar 31, 2026 - 21:13 nvd

Patch available

EUVD ID Assigned

Mar 12, 2026 - 22:55 euvd

EUVD-2026-11704

Analysis Generated

Mar 12, 2026 - 22:55 vuln.today

CVE Published

Mar 12, 2026 - 21:16 nvd

HIGH 7.5

Blast Radius

ecosystem impact

† from your stack dependencies † transitive graph · vuln.today resolves 4-path depth

28 npm packages depend on undici (16 direct, 23 indirect)

Ecosystem-wide dependent count for version 7.0.0.

DescriptionCVE.org

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

AnalysisAI

Node.js undici WebSocket client denial-of-service vulnerability allows remote attackers to crash the process by sending a malformed permessage-deflate compression parameter that bypasses validation and triggers an uncaught exception. The vulnerability exists because the client fails to properly validate the server_max_window_bits parameter before passing it to zlib, enabling any WebSocket server to terminate connected clients. No patch is currently available.