Buffer overflow in win32k.sys in the kernel-mode drivers in Microsoft Windows XP SP2 and SP3, Windows Server 2003 SP2, Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1, and Windows 7 SP1 allows local users to cause a denial of service (system hang) via a crafted application that leverages improper handling of objects in memory, aka "Win32k Buffer Overflow Vulnerability."