CVE-2026-109855

undici is an HTTP client library for Node.js. In versions 8.11.0 and 8.11.1, its experimental WebSocket client, which is enabled by default when HTTP/2 is allowed, mishandles a failed WebSocket handshake over HTTP/2: the request is already marked completed, so the abort becomes a no-op and the underlying HTTP/2 stream is left open with no error listener. When a malicious server then destroys the connection, the orphaned stream emits an unhandled error and the Node.js process exits. A remote, unauthenticated server can therefore crash any client that opens a WebSocket to it over HTTP/2, resulting in a denial of service. The issue is fixed in undici 8.11.2, and users should upgrade to 8.11.2 or later. As a workaround, set allowH2 to false to disable HTTP/2 for WebSocket connections, or avoid opening WebSocket connections to untrusted servers.

CVSS v3 7.5 HIGH

7.5^/10

CVSS v3 : HIGH

Vector :

Exploitability : 3.9 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://cna.openjsf.org/security-advisories.html	Vendor Advisory
https://github.com/nodejs/undici/security/advisories/GHSA-qq8j-7v2v-3rwp	Mitigation Vendor Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:nodejs:undici:*:*:*:*:*:node.js:*:*

History

19 Oct 2026, 20:46

Type	Values Removed	Values Added
CPE		cpe:2.3:a:nodejs:undici::::::node.js::*
References	~~() https://cna.openjsf.org/security-advisories.html -~~	() https://cna.openjsf.org/security-advisories.html - Vendor Advisory
References	~~() https://github.com/nodejs/undici/security/advisories/GHSA-qq8j-7v2v-3rwp -~~	() https://github.com/nodejs/undici/security/advisories/GHSA-qq8j-7v2v-3rwp - Mitigation, Vendor Advisory
First Time		Nodejs Nodejs undici

15 Oct 2026, 09:17

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-10-15 09:17

Updated : 2026-10-19 20:46

NVD link : CVE-2026-109855

Mitre link : CVE-2026-109855

CVE.ORG link : CVE-2026-109855

JSON object : View

Products Affected

nodejs

undici

CWE

CWE-248

Uncaught Exception

CWE-754

Improper Check for Unusual or Exceptional Conditions

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