The translate_desc function in drivers/vhost/vhost.c in the Linux kernel before 3.7 does not properly handle cross-region descriptors, which allows guest OS users to obtain host OS privileges by leveraging KVM guest OS privileges.
https://github.com/torvalds/linux/commit/bd97120fc3d1a11f3124c7c9ba1d91f51829eb85
https://bugzilla.redhat.com/show_bug.cgi?id=912905
http://www.openwall.com/lists/oss-security/2013/02/20/6
http://www.mandriva.com/security/advisories?name=MDVSA-2013:176
http://www.kernel.org/pub/linux/kernel/v3.x/patch-3.7.bz2
http://rhn.redhat.com/errata/RHSA-2013-0928.html
http://rhn.redhat.com/errata/RHSA-2013-0882.html
http://rhn.redhat.com/errata/RHSA-2013-0579.html
http://rhn.redhat.com/errata/RHSA-2013-0496.html
http://lists.opensuse.org/opensuse-security-announce/2013-07/msg00018.html