An anonymous reader writes "Google's security research database has after a 90 day timeout automatically undisclosed a Windows 8.1 vulnerability which Microsoft hasn't yet patched. By design the system call NtApphelpCacheControl() in ahcache.sys allows application compatibility data to be cached for quick reuse when new processes are created. A normal user can query the cache but cannot add new cached entries as the operation is restricted to administrators. This is checked in the function AhcVerifyAdminContext(). Long story short, the aforementioned function has a vulnerability where it doesn't correctly check the impersonation token of the caller to determine if the user is an administrator. It hasn't been fully verified if Windows 7 is vulnerable. For a passer-by it is also hard to tell whether Microsoft has even reviewed the issue reported by the Google researcher. The database has already one worried comment saying that automatically revealing a vulnerability just like that might be a bad idea."