{"id":"CVE-2026-109855","published":"2026-10-15T09:17:16.573","lastModified":"2026-10-15T20:38:04.303","description":"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.","cvssScore":7.5,"cvssSeverity":"HIGH","cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","cwes":["CWE-248","CWE-754"],"vendors":[],"products":[],"references":[{"url":"https://cna.openjsf.org/security-advisories.html","tags":[]},{"url":"https://github.com/nodejs/undici/security/advisories/GHSA-qq8j-7v2v-3rwp","tags":[]}],"exploitRefs":[{"url":"https://github.com/nodejs/undici/security/advisories/GHSA-qq8j-7v2v-3rwp","tags":[]}],"hasPoc":true,"ai":null}