KVM (Kernel-based Virtual Machine) is a full virtualization solution for Linux on AMD64 and Intel 64 systems. KVM is a Linux kernel module built for the standard Red Hat Enterprise Linux kernel.
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. (CVE-2012-3515)
This flaw did not affect the default use of KVM. Affected configurations were:
When guests were started from the command line ("/usr/libexec/qemu-kvm"), and without specifying a serial or parallel device that specifically does not use a virtual console (vc) back-end. (Note that Red Hat does not support invoking "qemu-kvm" from the command line on Red Hat Enterprise Linux 5.)
Guests that were managed via libvirt, such as when using Virtual Machine Manager (virt-manager), but that have a serial or parallel 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 KVM users should upgrade to these updated packages, which correct this issue. Note: The procedure in the Solution section must be performed before this update will take effect.