QEMU-KVM, as used in the Hypervisor (aka rhev-hypervisor) in Red Hat Enterprise Virtualization (RHEV) 2.2 and KVM 83, does not properly validate guest QXL driver pointers, which allows guest OS users to cause a denial of service (invalid pointer dereference and guest OS crash) or possibly gain privileges via unspecified vectors.
https://rhn.redhat.com/errata/RHSA-2010-0627.html