CVE-2026-92081
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.
- Score
- CVSS 3.1 5.9 Medium
- Status
- Awaiting Analysis - ce714d77-add3-4f53-aff5-83d477b104bb
- Published
- 2026-09-16
- Last modified
- 2026-09-16
- Weaknesses
- CWE-248
Affected products
References
- https://cna.openjsf.org/security-advisories.html
- https://github.com/fastify/fastify/security/advisories/GHSA-4mh8-r7rc-xpvc
