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.
- Score
- CVSS 3.1 7.5 High
- Status
- Analyzed - ce714d77-add3-4f53-aff5-83d477b104bb
- Published
- 2026-10-15
- Last modified
- 2026-10-19
- Weaknesses
- CWE-248, CWE-754
Affected products
References
- https://github.com/nodejs/undici/security/advisories/GHSA-qq8j-7v2v-3rwp
- https://cna.openjsf.org/security-advisories.html
