arch/x86/hvm/vmx/vmcs.c in the virtual-machine control structure (VMCS) implementation in the Linux kernel 2.6.18 on Red Hat Enterprise Linux (RHEL) 5 when an Intel platform without Extended Page Tables (EPT) functionality is used accesses VMCS fields without verifying hardware support for these fields which allows local users to cause a denial of service (host OS crash) by requesting a VMCS dump for a fully virtualized Xen guest.