CVE-2026-55501: 9router: Login brute-force protection bypass via spoofed X-Forwarded-For header

The 9router dashboard login rate limiter derives the client identity from the attacker-controlled X-Forwarded-For HTTP header. When 9router is directly exposed, or deployed behind a reverse proxy that does not overwrite untrusted forwarding headers, a remote attacker can rotate the X-Forwarded-For value on each login attempt and receive a fresh rate-limit bucket every time.

This bypasses the dashboard brute-force protection and makes the login lockout mechanism ineffective.