Vulnerabilidad · Publicado 04/09/2026
Fastify versiones anteriores a 5.12.2 presentan una validación incompleta de encabezados HTTP case-insensitive en esquemas de rutas. La transformación de minúsculas no se aplica correctamente en dependencias JSON Schema Draft 7, permitiendo que propiedades no normalizadas en el esquema causen comportamiento inesperado o bypass de validaciones. Esto afecta a aplicaciones Node.js en producción que dependen de validación estricta de encabezados para autenticación, autorización o filtrado de solicitudes.
fastify versions before 5.12.2 implement the case-insensitive nature of HTTP header names by lowercasing names in a route's header schema before compiling it, but the transformation is incomplete: it lowercases the properties keys and the root-level required array, and does not lowercase the trigger and dependent names inside the JSON Schema Draft 7 dependencies keyword. Because Node stores request header names in lowercase, a canonical-case dependency such as requiring an authentication header whenever a privileged-mode header is present never matches, and the presence assertion is silently skipped. An unauthenticated remote client can therefore send the header that activates a privileged branch while omitting the header the dependency was meant to require, bypassing the conditional check. Users should upgrade to fastify 5.12.2 or later.
Score: 7.5/10 — Severidad: HIGH — Estado NIST: Received
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
CWE-178
Publicado en NIST NVD.