VMware Workstation 6.5.x before 6.5.3 build 185404, VMware Player 2.5.x before 2.5.3 build 185404, VMware ACE 2.5.x before 2.5.3 build 185404, VMware Server 1.x before 1.0.10 build 203137 and 2.x before 2.0.2 build 203138, VMware Fusion 2.x before 2.0.6 build 196839, VMware ESXi 3.5 and 4.0, and VMware ESX 2.5.5, 3.0.3, 3.5, and 4.0, when Virtual-8086 mode is used, do not properly set the exception code upon a page fault (aka #PF) exception, which allows guest OS users to gain privileges on the guest OS by specifying a crafted value for the cs register.