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CVE-2026-92081

CVE-2026-92081 · fastify vulnerable to Denial of Service via unhandled exception on HTTP/2 trailer responses

This page contains facts from public vulnerability sources. Check the original advisory before updating.

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.

CVSS 5.9 · Medium · EPSS 0.4% · Fix available

Published
Updated

Stack: node

Affected products and versions

  • fastify

    Versions
    • ≥ 0, < 5.12.5: Affected (semver)
    • 5.12.5: Not affected (semver)

    Update to 5.12.5

  • fastify npm

    Affected ranges
    • SEMVER: < 5.12.5

    Update to 5.12.5

Original sources

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