Skip to content
CVE PROGRAM SOURCE RECORD5.9 Medium

CVE-2026-92081

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.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

fastify fastify

Default version status: unaffected

  • 0 to < 5.12.5affected
  • 5.12.5unaffected
pkg:npm/fastify

References