CVE-2026-92081
fastify vulnerable to Denial of Service via unhandled exception on HTTP/2 trailer responses
- State
- Published
- Severity
- 5.9 Medium
- Published
- Sep 16, 2026
- Updated
- Sep 16, 2026
- Reserved
- Sep 15, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 5.9 Medium | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H | openjs |
Weaknesses
- CWE-248 Uncaught Exception
Affected Products
| Product | Versions |
|---|---|
fastifyfastify |
|
References
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