An elevation of privilege vulnerability exists when the Windows Virtual Hard Disk Drive fails to properly handle user access to certain files. An attacker who successfully exploited the vulnerability could manipulate files in locations not intended to be available to the user.
To exploit the vulnerability, an attacker would need access to the local system and the ability to execute a specially crafted application on the system.
The security update addresses the vulnerability by correcting how the kernel API restricts access to these files.