VMware Workstation before 5.5.4, when running a 64-bit Windows guest on a 64-bit host, allows local users to "corrupt the virtual machine's register context" by debugging a local program and stepping into a "syscall instruction."
VMware Workstation before 5.5.4 allows attackers to cause a denial of service against the guest OS by causing the virtual machine process (VMX) to store malformed configuration information.