An information disclosure vulnerability exists when Windows Hyper-V on a host operating system fails to properly validate input from an authenticated user on a guest operating system. To exploit the vulnerability, an attacker on a guest operating system could run a specially crafted application that could cause the Hyper-V host operating system to disclose memory information. An attacker who successfully exploited the vulnerability could gain access to information on the Hyper-V host operating system. The security update addresses the vulnerability by correcting how Hyper-V validates guest operating system user input.