A vulnerability has been identified in SIPROTEC 4 and SIPROTEC Compact relays equipped with EN100 Ethernet communication modules (All versions). Specially crafted packets sent to port 50000/UDP of the EN100 Ethernet communication modules could cause a Denial-of-Service of the affected device. A manual reboot is required to recover the service of the device. At the time of advisory publication no public exploitation of this security vulnerability was known to Siemens.