{"id":"CVE-2026-92081","aliases":["GHSA-4mh8-r7rc-xpvc"],"url":"https://o3.security/vulnerability/CVE-2026-92081","summary":"fastify vulnerable to Denial of Service via unhandled exception on HTTP/2 trailer responses","details":"### Impact\n\n`fastify` crashes with an uncaught `ERR_HTTP2_INVALID_CONNECTION_HEADERS` exception when a route that registers a response trailer via `reply.trailer()` is served over HTTP/2. Fastify unconditionally adds the `Transfer-Encoding: chunked` header when a trailer is set, which is forbidden on HTTP/2, so Node.js throws while serializing the response headers. The exception is not caught and becomes an uncaughtException, terminating the Node.js process.\n\nOne unauthenticated HTTP/2 request to any route that uses trailers is enough to crash the server, dropping all in-flight requests, and the request can be repeated to keep the process down. Applications are affected only when HTTP/2 is enabled (`http2: true`) and at least one route registers a trailer. HTTP/1.x responses are not affected.\n\n### Patches\n\nUpgrade to `fastify` `5.12.5` or later.\n\n### Workarounds\n\nAvoid registering response trailers with `reply.trailer()` on routes served over HTTP/2 until upgrading.","published":"2026-09-16T08:52:49.757Z","modified":"2026-10-21T03:00:13.157545674Z","cvss":{"score":5.9,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"npm","name":"fastify","fixedVersion":"5.12.5"}],"fix":{"url":"https://github.com/fastify/fastify/commit/ad06a4c3fe8a944a904f38068249b18b8f552e90","label":"fastify/fastify@ad06a4c"},"references":[{"type":"ADVISORY","url":"https://cna.openjsf.org/security-advisories.html"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/92xxx/CVE-2026-92081.json"},{"type":"ADVISORY","url":"https://github.com/fastify/fastify/security/advisories/GHSA-4mh8-r7rc-xpvc"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-92081"},{"type":"WEB","url":"https://github.com/fastify/fastify/issues/6574"},{"type":"WEB","url":"https://github.com/fastify/fastify/commit/ad06a4c3fe8a944a904f38068249b18b8f552e90"},{"type":"PACKAGE","url":"https://github.com/fastify/fastify"},{"type":"WEB","url":"https://github.com/fastify/fastify/releases/tag/v5.12.5"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-21T03:00:13.157545674Z"}}