KVM (Kernel-based Virtual Machine) is a full virtualization solution for Linux on AMD64 and Intel 64 systems. The qemu-kvm-rhev packages form the user-space component for running virtual machines using KVM.
A flaw was found in the way QEMU-KVM emulated the e1000 network interface card when the host was configured to accept jumbo network frames, and a guest using the e1000 emulated driver was not. A remote attacker could use this flaw to crash the guest or, potentially, execute arbitrary code with root privileges in the guest. (CVE-2012-6075)
All users of qemu-kvm-rhev are advised to upgrade to these updated packages, which correct this issue. After installing this update, shut down all running virtual machines. Once all virtual machines have shut down, start them again for this update to take effect.