Virtual servers in F5 BIG-IP systems 11.5.0, 11.5.1 before HF11, 11.5.2, 11.5.3, 11.5.4 before HF2, 11.6.0 before HF8, 11.6.1 before HF1, 12.0.0 before HF4, and 12.1.0 before HF2, when configured with the HTTP Explicit Proxy functionality or SOCKS profile, allow remote attackers to modify the system configuration, read system files, and possibly execute arbitrary code via unspecified vectors.