CVE-2026-84504

A flaw was found in fastify. An authenticated low-privilege caller can exploit a vulnerability where the framework incorrectly processes the result of an Ajv asynchronous async validator. If a request body contains a root-level property named 'value', fastify replaces the entire request body with...

CVE-2026-84504 fastify vulnerable to request body replacement via an async validation result collision

fastify versions before 5.12.2 treat the object resolved by a successful Ajv async validator as the value result protocol used by custom validator compilers. If a request that passes its route schema contains a property named value at the root, fastify replaces the entire request body with that...

EUVD-2026-70984

fastify versions before 5.12.2 treat the object resolved by a successful Ajv async validator as the value result protocol used by custom validator compilers. If a request that passes its route schema contains a property named value at the root, fastify replaces the entire request body with that...

PT-2026-85451

fastify versions before 5.12.2 treat the object resolved by a successful Ajv async validator as the value result protocol used by custom validator compilers. If a request that passes its route schema contains a property named value at the root, fastify replaces the entire request body with that...