A vulnerability has been identified in SIMATIC CP 1626 (All versions), SIMATIC ET 200SP Open Controller CPU 1515SP PC (incl. SIPLUS variants) (All versions), SIMATIC ET 200SP Open Controller CPU 1515SP PC2 (incl. SIPLUS variants) (All versions < V20.8), SIMATIC HMI Panel (incl. SIPLUS variants) (All versions), SIMATIC NET PC Software V14 (All versions < V14 SP1 Update 14), SIMATIC NET PC Software V15 (All versions), SIMATIC S7-1200 CPU family (incl. SIPLUS variants) (All versions < V4.4.0), SIMATIC S7-1500 CPU family (incl. related ET200 CPUs and SIPLUS variants) (All versions < V2.8.1), SIMATIC S7-1500 Software Controller (All versions < V20.8), SIMATIC S7-PLCSIM Advanced (All versions < V3.0), SIMATIC STEP 7 (TIA Portal) (All versions < V16), SIMATIC WinCC (TIA Portal) (All versions < V16), SIMATIC WinCC OA (All versions < V3.16 P013), SIMATIC WinCC Runtime Advanced (All versions < V16), SIMATIC WinCC Runtime Professional (All versions < V16), TIM 1531 IRC (incl. SIPLUS NET variants) (All versions < V2.1). Affected devices contain a message protection bypass vulnerability due to certain properties in the calculation used for integrity protection. This could allow an attacker in a Man-in-the-Middle position to modify network traffic sent on port 102/tcp to the affected devices.