{"id":"CVE-2026-92081","state":"PUBLISHED","title":"fastify vulnerable to Denial of Service via unhandled exception on HTTP/2 trailer responses","description":"fastify is a fast and low-overhead web framework for Node.js. In versions before 5.12.5, when a route registers a response trailer via reply.trailer() and is served over HTTP/2, fastify unconditionally sets the Transfer-Encoding: chunked header, which is forbidden on HTTP/2, so Node.js throws while serializing the response headers. The exception is not caught and becomes an uncaughtException, so a single unauthenticated HTTP/2 request to any route that uses trailers crashes the server process and drops all in-flight requests, and it can be repeated on every restart. The issue is fixed in fastify 5.12.5, and users should upgrade to 5.12.5 or later. As a workaround, avoid registering response trailers with reply.trailer() on routes served over HTTP/2 until upgrading.","publishedAt":"2026-09-16T08:52:49.757Z","updatedAt":"2026-09-16T14:00:59.305Z","severity":{"score":5.9,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H","source":"openjs"},"assigner":"openjs","products":["fastify fastify"],"affected":[{"vendor":"fastify","product":"fastify","packageURL":"pkg:npm/fastify","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThan":"5.12.5","versionType":"semver"},{"version":"5.12.5","status":"unaffected","versionType":"semver"}]}],"references":["https://github.com/fastify/fastify/security/advisories/GHSA-4mh8-r7rc-xpvc","https://cna.openjsf.org/security-advisories.html"],"weaknesses":["CWE-248"],"ingestedAt":"2026-10-29T20:13:34.582Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/92xxx/CVE-2026-92081.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-92081","state":"PUBLISHED","datePublished":"2026-09-16T08:52:49.757Z","dateUpdated":"2026-09-16T14:00:59.305Z","assignerShortName":"openjs","assignerOrgId":"ce714d77-add3-4f53-aff5-83d477b104bb","dateReserved":"2026-09-15T12:55:43.189Z"},"containers":{"cna":{"title":"fastify vulnerable to Denial of Service via unhandled exception on HTTP/2 trailer responses","descriptions":[{"lang":"en","value":"fastify is a fast and low-overhead web framework for Node.js. In versions before 5.12.5, when a route registers a response trailer via reply.trailer() and is served over HTTP/2, fastify unconditionally sets the Transfer-Encoding: chunked header, which is forbidden on HTTP/2, so Node.js throws while serializing the response headers. The exception is not caught and becomes an uncaughtException, so a single unauthenticated HTTP/2 request to any route that uses trailers crashes the server process and drops all in-flight requests, and it can be repeated on every restart. The issue is fixed in fastify 5.12.5, and users should upgrade to 5.12.5 or later. As a workaround, avoid registering response trailers with reply.trailer() on routes served over HTTP/2 until upgrading."}],"affected":[{"vendor":"fastify","product":"fastify","packageURL":"pkg:npm/fastify","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThan":"5.12.5","versionType":"semver"},{"version":"5.12.5","status":"unaffected","versionType":"semver"}]}],"references":[{"url":"https://github.com/fastify/fastify/security/advisories/GHSA-4mh8-r7rc-xpvc"},{"url":"https://cna.openjsf.org/security-advisories.html"}],"metrics":[{"format":"CVSS","cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H","baseScore":5.9,"baseSeverity":"MEDIUM"},"scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-248","lang":"en","description":"CWE-248: Uncaught Exception","type":"CWE"}]}],"providerMetadata":{"shortName":"openjs","orgId":"ce714d77-add3-4f53-aff5-83d477b104bb","dateUpdated":"2026-09-16T08:52:49.757Z"},"credits":[{"lang":"en","type":"remediation developer","value":"mcollina"},{"lang":"en","type":"remediation reviewer","value":"UlisesGascon"},{"lang":"en","type":"reporter","value":"zerovulnlabs"}],"x_generator":{"engine":"cve-kit 1.0.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-09-16T14:00:06.966478Z","id":"CVE-2026-92081","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-09-16T14:00:59.305Z"}}]}}}