A denial of service vulnerability exists when Hyper-V on a Windows Server fails to properly handle specially crafted network packets.To exploit the vulnerability, an attacker would send specially crafted network packets to the Hyper-V Server.The security update addresses the vulnerability by resolving the conditions where Hyper-V would fail to properly handle these network packets., aka 'Windows Hyper-V Denial of Service Vulnerability'.
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-0909