CVE-2026-120215 (GCVE-0-2026-120215)
Vulnerability from cvelistv5 – Published: 2026-11-02 10:20 – Updated: 2026-11-02 17:04
VLAI
EPSS
VEX
Title
@fastify/cors vulnerable to Denial of Service on a CORS preflight with the onSend hook
Summary
@fastify/cors is the CORS plugin for the Fastify web framework. In versions 8.2.0 through 11.3.x, an application that registers the plugin with the non-default onSend hook option crashes on a CORS preflight. On an OPTIONS request that carries the Origin and Access-Control-Request-Method headers, the plugin calls reply.send from inside the onSend hook and re-enters the send pipeline, so a second write of the response headers throws an uncaught ERR_HTTP_HEADERS_SENT that can terminate the Node.js process when no process-level handler is installed. An unauthenticated remote client can trigger this with a single preflight request, so the impact is availability only, and exploitation requires the non-default onSend configuration. The issue is fixed in @fastify/cors 11.4.0, where onSend is no longer an accepted hook value and registration fails with a clear error instead of crashing at request time, and users should upgrade to 11.4.0 or later. As a workaround, use any other hook such as the default onRequest, or set preflight to false.
Severity
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-11-02 17:03 UTC
CWE
- CWE-248 - Uncaught Exception
Assigner
References
Impacted products
1 product
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| @fastify/cors | @fastify/cors |
Affected:
8.2.0 , < 11.4.0
(semver)
Unaffected: 11.4.0 (semver) |
guessed |
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Browse all ATT&CK techniques and the vulnerabilities related to each.
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