CVE-2026-84428

A flaw was found in fastify. Due to incomplete case normalization of HTTP header names within a route's header schema, specifically within the JSON Schema Draft 7 dependencies keyword, an unauthenticated remote attacker can bypass intended conditional checks. This allows the attacker to send...

CVE-2026-84428: Improper Handling of Case Sensitivity

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...