A vulnerability has been identified in SIMATIC CP443-1 OPC UA (All versions), SIMATIC ET 200 Open Controller CPU 1515SP PC2 (All versions < V2.7), SIMATIC HMI Comfort Outdoor Panels 7" & 15" (All versions), SIMATIC HMI Comfort Panels 4" - 22" (All versions), SIMATIC HMI KTP Mobile Panels KTP400F, KTP700, KTP700F, KTP900 und KTP900F (All versions), SIMATIC IPC DiagMonitor (All versions), SIMATIC NET PC Software (All versions >= V7.1), SIMATIC RF188C (All versions < V1.1.0), SIMATIC RF600R (All versions < V3.2.1), SIMATIC S7-1500 CPU family (All versions >= V2.5 < V2.6.1), SIMATIC S7-1500 Software Controller (All versions between V2.5 (including) and V2.7 (excluding)), SIMATIC WinCC OA (All versions < V3.15-P018), SIMATIC WinCC Runtime Advanced (All versions), SINEC-NMS (All versions), SINEMA Server (All versions < V14 SP2), SINUMERIK OPC UA Server (All versions < V2.1), TeleControl Server Basic (All versions). Specially crafted network packets sent to affected devices on port 4840/tcp could allow an unauthenticated remote attacker to cause a Denial-of-Service condition of the OPC communication or crash the device. The security vulnerability could be exploited by an attacker with network access to the affected systems. Successful exploitation requires no system privileges and no user interaction. An attacker could use the vulnerability to compromise availability of the OPC communication. At the time of advisory publication no public exploitation of this security vulnerability was known.