Fastify's Content-Type header tab character allows body validation bypass
A validation bypass vulnerability exists in Fastify where request body validation schemas specified by Content-Type can be completely circumvented. By appending a tab character (\t) followed by arbitrary content to the Content-Type header, attackers can bypass body validation while the server still processes the body as the original content type. For example, a request with Content-Type: application/json\ta will bypass JSON schema validation but still be parsed as JSON. This vulnerability …