[ CVE-2026-92081 · Published 16 Sep 2026 ]
fastify vulnerable to Denial of Service via unhandled exception on HTTP/2 trailer responses
[ Description ]Official 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.
[ Fixes ]Fixes and patches
- fastify 5.12.5Fixed version · GitHub Advisories · npm package fastify: upgrade to 5.12.5 or later (affected < 5.12.5)
[ Packages ]Affected open-source packages
- fastify npmAffected < 5.12.5 · fixed in 5.12.5 · GHSA-4mh8-r7rc-xpvc