KVM (Kernel-based Virtual Machine) is a full virtualization solution for Linux on AMD64 and Intel 64 systems.
A flaw was found in the way QEMU's AMD PCnet Ethernet emulation handled multi-TMD packets with a length above 4096 bytes. A privileged guest user in a guest with an AMD PCNet ethernet card enabled could potentially use this flaw to execute arbitrary code on the host with the privileges of the hosting QEMU process. (CVE-2015-3209)
Red Hat would like to thank Matt Tait of Google's Project Zero security team for reporting this issue.
All kvm users are advised to upgrade to these updated packages, which contain a backported patch to correct this issue. Note: The procedure in the Solution section must be performed before this update will take effect.