In F5 BIG-IP 13.0.0, 12.1.0-12.1.2, 11.6.1, 11.5.1-11.5.5, or 11.2.1 the Apache modules apache_auth_token_mod and mod_auth_f5_auth_token.cpp allow possible unauthenticated bruteforce on the em_server_ip authorization parameter to obtain which SSL client certificates used for mutual authentication between BIG-IQ or Enterprise Manager (EM) and managed BIG-IP devices.