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.