A vulnerability in zenml-io/zenml versions 0.57.0 through 0.94.2 allows an attacker to bypass rate-limiting on the POST /api/v1/login and self password-change endpoints by rotating the X-Forwarded-For header. The rate limiter keys requests by request.client.host, which is derived from the X-Forwarded-For header when Uvicorn is launched with --proxy-headers --forwarded-allow-ips *. This configuration allows clients to control the value of request.client.host, effectively bypassing rate-limiting protections. This vulnerability leaves the affected endpoints open to unthrottled credential guessing attacks.