A vulnerability has been identified in Firmware variant PROFINET IO for EN100 Ethernet module : All versions < V1.04.01; Firmware variant Modbus TCP for EN100 Ethernet module : All versions < V1.11.00; Firmware variant DNP3 TCP for EN100 Ethernet module : All versions < V1.03; Firmware variant IEC 104 for EN100 Ethernet module : All versions < V1.21; EN100 Ethernet module included in SIPROTEC Merging Unit 6MU80 : All versions < 1.02.02; SIPROTEC 7SJ686 : All versions < V 4.87; SIPROTEC 7UT686 : All versions < V 4.02; SIPROTEC 7SD686 : All versions < V 4.05; SIPROTEC 7SJ66 : All versions < V 4.30. Attackers with network access to the device's web interface (port 80/tcp) could possibly circumvent authentication and perform certain administrative operations. A legitimate user must be logged into the web interface for the attack to be successful.