<p>A denial of service vulnerability exists when Microsoft Hyper-V on a host server fails to properly validate specific malicious data from a user on a guest operating system.</p> <p>To exploit the vulnerability, an attacker who already has a privileged account on a guest operating system, running as a virtual machine, could run a specially crafted application.</p> <p>The security update addresses the vulnerability by resolving the conditions where Hyper-V would fail to handle these requests.</p>