{"id":"CVE-2026-109855","revision":"694f8d38e589499fba12f777e638867b","records":[{"revision":"694f8d38e589499fba12f777e638867b","observedAt":"2026-10-27T16:45:50.731+00:00","statement":{"source":"nvd","id":"CVE-2026-109855","aliases":[],"title":"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 …","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.","state":0,"publishedAt":"2026-10-15T09:17:16.573+00:00","modifiedAt":"2026-10-19T20:46:49.4+00:00","affected":[],"metrics":[{"system":"CVSS 3.1 · ce714d77-add3-4f53-aff5-83d477b104bb · Secondary","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5,"severity":"HIGH"}],"references":["https://cna.openjsf.org/security-advisories.html","https://github.com/nodejs/undici/security/advisories/GHSA-qq8j-7v2v-3rwp"],"sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-109855","license":"NIST NVD usage terms; underlying source attribution retained","enrichment":{"sourceStatus":"Analyzed","weaknesses":["CWE-248","CWE-754"],"productCriteria":["cpe:2.3:a:nodejs:undici:*:*:*:*:*:node.js:*:*"],"sourceDates":{"published":"2026-10-15T09:17:16.573","lastModified":"2026-10-19T20:46:49.400"},"relatedAdvisories":[],"note":"NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON."},"key":"nvd:CVE-2026-109855","identifiers":["CVE-2026-109855"]},"retained":false,"historicalAffected":[]}],"coverage":[]}