A vulnerability has been identified in SIMATIC S7-400 (incl. F) V6 and below (All versions), SIMATIC S7-400 PN/DP V7 (incl. F) (All versions), SIMATIC S7-400H V4.5 and below (All versions), SIMATIC S7-400H V6 (All versions), SIMATIC S7-410 (All versions < V8.2.1). Sending of specially crafted packets to port 102/tcp via Ethernet interface via PROFIBUS or Multi Point Interfaces (MPI) could cause a Denial-of-Service condition on affected devices. Flashing with a firmware image may be required to recover the CPU. Successful exploitation requires an attacker to have network access to port 102/tcp via Ethernet interface or to be able to send messages via PROFIBUS or Multi Point Interfaces (MPI) to the device. No user interaction is required. If no access protection is configured, no privileges are required to exploit the security vulnerability. The vulnerability could allow causing a Denial-of-Service condition of the core functionality of the CPU, compromising the availability of the system. At the time of advisory publication no public exploitation of this security vulnerability was known.