{"id":"CVE-2026-109855","sourceIdentifier":"ce714d77-add3-4f53-aff5-83d477b104bb","published":"2026-10-15T09:17:16.573","lastModified":"2026-10-19T20:46:49.400","vulnStatus":"Analyzed","cveTags":[],"descriptions":[{"lang":"en","value":"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."}],"affected":[{"source":"ce714d77-add3-4f53-aff5-83d477b104bb","affectedData":[{"vendor":"undici","product":"undici","defaultStatus":"unaffected","packageURL":"pkg:npm/undici","versions":[{"version":"8.11.0","lessThan":"8.11.2","versionType":"semver","status":"affected"},{"version":"8.11.2","versionType":"semver","status":"unaffected"}]}]}],"metrics":{"cvssMetricV31":[{"source":"ce714d77-add3-4f53-aff5-83d477b104bb","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","baseScore":7.5,"baseSeverity":"HIGH","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"HIGH"},"exploitabilityScore":3.9,"impactScore":3.6}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"timestamp":"2026-10-15T14:21:59.498708Z","id":"CVE-2026-109855","options":[{"exploitation":"none"},{"automatable":"yes"},{"technicalImpact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}]},"weaknesses":[{"source":"ce714d77-add3-4f53-aff5-83d477b104bb","type":"Secondary","description":[{"lang":"en","value":"CWE-248"},{"lang":"en","value":"CWE-754"}]}],"configurations":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:a:nodejs:undici:*:*:*:*:*:node.js:*:*","versionStartIncluding":"8.11.0","versionEndExcluding":"8.11.2","matchCriteriaId":"BF06FDAA-47A8-46C9-AF8E-B65A9DA4A99D"}]}]}],"references":[{"url":"https://cna.openjsf.org/security-advisories.html","source":"ce714d77-add3-4f53-aff5-83d477b104bb","tags":["Vendor Advisory"]},{"url":"https://github.com/nodejs/undici/security/advisories/GHSA-qq8j-7v2v-3rwp","source":"ce714d77-add3-4f53-aff5-83d477b104bb","tags":["Mitigation","Vendor Advisory"]}]}