CVE-2026-92081 · GHSA-4mh8-r7rc-xpvc
fastify vulnerable to Denial of Service via unhandled exception on HTTP/2 trailer responses
- Risk score
- 47/100
- CVSS
- 5.9 v3.1
- Exploit chance (30 days)
- 0.4%
- Published
- 30 Sep 2026
Open in the live forecast Today's forecast
What to know
- What it is
- fastify crashes with an uncaught ERR_HTTP2_INVALID_CONNECTION_HEADERS exception when a route that registers a response trailer via reply.trailer() is served over HTTP/2. Fastify unconditionally adds the Transfer-Encoding: chunked header when a trailer is set, which is forbidden on HTTP/2, so Node.js throws while seria…
- Affected
- fastify (npm) < 5.12.5
- Fix
- Upgrade fastify to 5.12.5 or later.
- Exploitation
- No known exploitation
Story map
At a glance
fastify: Amber, patch this week. Fastify routes a malformed URL under one plugin prefix to the custom not-found handler of a different sibling plugin, invoking the handler registered last and skipping the preHandler declared in its setNotFoundHandler(). When the request method has no route in the main router, a malformed request target reaches Fastif…
The flaws
- CVE-2026-92081: Fastify vulnerable to Denial of Service via unhandled exception on HTTP/2 trailer responses (CVSS 5.9 · EPSS 0%)
- CVE-2026-76169: Fastify vulnerable to authentication bypass via malformed URLs reaching encapsulated not-found handlers (CVSS 7.5 · EPSS 1%)
- CVE-2026-84428: Fastify vulnerable to header validation bypass via incomplete schema case normalization (CVSS 7.5 · EPSS 1%)
- CVE-2026-84469: Fastify vulnerable to request validation bypass via skipped boolean false schemas (CVSS 7.5 · EPSS 0%)
The fix
Fix: Upgrade fastify to 5.12.2 or later.
Who is exposed: fastify (npm) >= 4.0.0, < 5.12.2
Where it stands
- No known exploitation
Connects to
- Same weakness: CWE-248 (CWE-248). 63 other warnings in 30 days
Why it is Yellow
- CVSS 5.9 medium
- On your watchlist: npm
Affected packages
| Package | Ecosystem | Vulnerable | Fixed in |
|---|---|---|---|
| fastify | npm | < 5.12.5 | 5.12.5 |
References
- https://github.com/advisories/GHSA-4mh8-r7rc-xpvc
- https://github.com/fastify/fastify/security/advisories/GHSA-4mh8-r7rc-xpvc
- https://nvd.nist.gov/vuln/detail/CVE-2026-92081
- https://github.com/fastify/fastify/issues/6574
- https://github.com/fastify/fastify/commit/ad06a4c3fe8a944a904f38068249b18b8f552e90
- https://cna.openjsf.org/security-advisories.html
- https://github.com/fastify/fastify/releases/tag/v5.12.5
- https://github.com/advisories/GHSA-4mh8-r7rc-xpvc
Original description
### Impact `fastify` crashes with an uncaught `ERR_HTTP2_INVALID_CONNECTION_HEADERS` exception when a route that registers a response trailer via `reply.trailer()` is served over HTTP/2. Fastify unconditionally adds the `Transfer-Encoding: chunked` header when a trailer is set, which is forbidden on HTTP/2, so Node.js throws while serializing the response headers. The exception is not caught and becomes an uncaughtException, terminating the Node.js process. One unauthenticated HTTP/2 request to any route that uses trailers is enough to crash the server, dropping all in-flight requests, and the request can be repeated to keep the process down. Applications are affected only when HTTP/2 is enabled (`http2: true`) and at least one route registers a trailer. HTTP/1.x responses are not affected. ### Patches Upgrade to `fastify` `5.12.5` or later. ### Workarounds Avoid registering response trailers with `reply.trailer()` on routes served over HTTP/2 until upgrading.
Last activity 30 Sep 2026. Patch Forecast updates every hour.