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.