lgtosync.sys in VMware Workstation 9.x before 9.0.3, VMware Player 5.x before 5.0.3, VMware Fusion 5.x before 5.0.4, VMware ESXi 4.0 through 5.1, and VMware ESX 4.0 and 4.1, when a 32-bit Windows guest OS is used, allows guest OS users to gain guest OS privileges via an application that performs a crafted memory allocation.