Open redirect via scheme-relative directory path

Open redirect in Fastify @fastify/static before 4.2.4 allows remote attackers to send Firefox users to arbitrary sites via crafted paths. The directory redirect handler parses the raw request URL with Node.js url.parse and places its pathname directly into a 301 Location header, preserving a leading double slash that Firefox interprets as a scheme-relative host. Exploitation requires the nondefault redirect:true option and a victim following the crafted link; the redirect can move that Firefox session to an attacker-chosen origin.