HMS Networks Ewon Flexy with firmware before 15.0s4, Cosy+ with firmware 22.xx before 22.1s6, and Cosy+ with firmware 23.xx before 23.0s3 allows unauthenticated attackers to cause a Denial of Service by using a specially crafted HTTP request that leads to a reboot of the device, provided they have access to the device's GUI.
https://www.hms-networks.com/p/flexy20500-00ma-ewon-flexy-205