fastify vulnerable to Denial of Service via unhandled exception on HTTP/2 trailer responses
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.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2026-92081
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 4 Nov 2026, 18:35 UTC · Revision 1
Source evidence
fastify vulnerable to Denial of Service via unhandled exception on HTTP/2 trailer responses
core-osv · Original sourcePublished 16 Sept 2026, 08:52 UTC
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.
osv:CVE-2026-92081
Complete source record
{
"id": "33a972f0f88ab84d8aabf23f31bf3a094f5a283db00fa617100ac8b117090e28",
"url": "https://osv.dev/vulnerability/CVE-2026-92081",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "fastify vulnerable to Denial of Service via unhandled exception on HTTP/2 trailer responses",
"summary": "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.",
"evidence": "osv:CVE-2026-92081",
"products": [],
"severity": "medium",
"structured": {
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"aliases": [
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"GHSA-4mh8-r7rc-xpvc"
],
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"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H"
}
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"modified": "2026-10-28T02:30:38.476722774Z",
"provider": "osv",
"references": [
"https://cna.openjsf.org/security-advisories.html",
"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/92xxx/CVE-2026-92081.json",
"https://github.com/fastify/fastify/security/advisories/GHSA-4mh8-r7rc-xpvc",
"https://nvd.nist.gov/vuln/detail/CVE-2026-92081"
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"source_id": "core-osv",
"document_id": 505745,
"published_at": "2026-09-16T08:52:49.757+00:00"
}