VMware vCenter Server 4.0 before Update 4b and 4.1 before Update 3a, VMware VirtualCenter 2.5, VMware vSphere Client 4.0 before Update 4b and 4.1 before Update 3a, VMware VI-Client 2.5, VMware ESXi 3.5 through 4.1, and VMware ESX 3.5 through 4.1 do not properly implement the management authentication protocol, which allow remote servers to execute arbitrary code or cause a denial of service (memory corruption) via unspecified vectors.
The VMX process in VMware ESXi 3.5 through 4.1 and ESX 3.5 through 4.1 does not properly handle RPC commands, which allows guest OS users to cause a denial of service (memory overwrite and process crash) or possibly execute arbitrary code on the host OS via vectors involving data pointers.