A Server-Side Request Forgery (SSRF) vulnerability exists in the POST /worker_generate_stream API endpoint of the Controller API Server in lm-sys/fastchat, as of commit e208d5677c6837d590b81cb03847c0b9de100765. This vulnerability allows attackers to exploit the victim controller API servers credentials to perform unauthorized web actions or access unauthorized web resources by combining it with the POST /register_worker endpoint.
The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.