The EPATHOBJ::bFlatten function in win32k.sys in Microsoft Windows XP SP2 and SP3 Windows Server 2003 SP2 Windows Vista SP2 Windows Server 2008 SP2 and R2 SP1 Windows 7 SP1 Windows 8 Windows Server 2012 and Windows RT does not check whether linked-list traversal is continually accessing the same list member which allows local users to cause a denial of service (infinite traversal) via vectors that trigger a crafted PATHRECORD chain.