A proof-of-concept (PoC) denial of service exploit has been published by Danish security researcher Ollypwn. The vulnerability affects the Remote Desktop Gateway (RD Gateway) component on Windows Server (2012, 2012 R2, 2016, and 2019) devices. RD Gateway is used to fence off Remote Desktop servers on internal networks from Internet connections. The two vulnerabilities were patched by Microsoft as part of the January Patch Tuesday, on January 14, and they are both pre-authentication remote code execution rated by Redmond as critical.
Source: https://www.bleepingcomputer.com/news/security/dos-exploit-poc-released-for-critical-windows-rdp-gateway-bugs/