A remote code execution vulnerability exists in the VM Host Agent Service of Remote Desktop Virtual Host role when it fails to properly validate input from an authenticated user on a guest operating system. To exploit the vulnerability, an attacker could issue a specially crafted certificate on the guest operating system that could cause the VM host agent service on the host operating system to execute arbitrary code. The Remote Desktop Virtual Host role is not enabled by default. An attacker who successfully exploited the vulnerability could execute arbitrary code on the host operating system. The security update addresses the vulnerability by correcting how VM host agent service validates guest operating system user input.