KVM is a full virtualization solution for Linux on AMD64 and Intel 64 systems. qemu-kvm is the user-space component for running virtual machines using KVM. A flaw was found in the way QEMU handled VT100 terminal escape sequences when emulating certain character devices. A guest user with privileges to write to a character device that is emulated on the host using a virtual console back-end could use this flaw to crash the qemu-kvm process on the host or, possibly, escalate their privileges on the host. This flaw did not affect the default use of KVM. Affected configurations were: * When guests were started from the command line without the -nodefaults option, and also without specifying a serial or parallel device, or a virtio-console device, that specifically does not use a virtual console back-end. * Guests that were managed via libvirt, such as when using Virtual Machine Manager , but that have a serial or parallel device, or a virtio-console device, that uses a virtual console back-end. By default, guests managed via libvirt will not use a virtual console back-end for such devices. Red Hat would like to thank the Xen project for reporting this issue. All users of qemu-kvm should upgrade to these updated packages, which resolve 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.