The VBoxDrvNtDeviceControl function in VBoxDrv.sys in Sun xVM VirtualBox before 1.6.4 uses the METHOD_NEITHER communication method for IOCTLs and does not properly validate a buffer associated with the Irp object, which allows local users to gain privileges by opening the \\.\VBoxDrv device and calling DeviceIoControl to send a crafted kernel address.

More... (http://nvd.nist.gov/nvd.cfm?cvename=CVE-2008-3431)