Is there a public exploit for CVE-2026-120216?

No public exploit for CVE-2026-120216 was found in Exploit-DB, Metasploit, Nuclei templates or public proof-of-concept repositories. That is an absence of evidence rather than proof that none exists.

How severe is CVE-2026-120216?

CVE-2026-120216 scores CVSS 5.9 (v3.1), rated medium.

What does CVE-2026-120216 affect?

CVE-2026-120216 affects fastify fastify.

5.9 Medium

fastify is a web framework for Node.js.

CVE-2026-120216

fastify is a web framework for Node.js. In versions 5.8.0 through 5.12.7, when the server is configured with a nonzero handlerTimeout and a route returns a streaming response, a request whose stream has already sent its headers but stays open past the timeout crashes the server. When the timeout fires, Fastify tries to send a new error response on a response that has already started, raising an uncaught ERRHTTPHEADERSSENT that terminates the Node.js process and interrupts any other in-flight requests. An unauthenticated remote client can trigger this with a single request to an affected streaming endpoint, so the impact is availability only, and exploitation requires the non-default handlerTimeout to be set. The default handlerTimeout of 0 is not affected. The issue is fixed in fastify 5.12.8, and users should upgrade to 5.12.8 or later. As a workaround, set handlerTimeout to 0, which disables the affected timeout path.

Assessment

CVSS: 5.9 (v3.1)
Severity: Medium
Known exploited: Not listed in CISA KEV
Exploit availability: Nothing found in Exploit-DB, Metasploit, Nuclei or public PoC repositories
Published: 2 November 2026
Last updated: 2 November 2026
Affected: fastify · fastify
Assigner: openjs

CVSS vectorCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

At the source

EUVD (ENISA)

References

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