The (1) qemuDomainMigratePerform and (2) qemuDomainMigrateFinish2 functions in qemu/qemu_driver.c in libvirt do not unlock the domain when an ACL check fails, which allow local users to cause a denial of service via unspecified vectors.
http://www.ubuntu.com/usn/USN-2867-1
http://secunia.com/advisories/61111
http://rhn.redhat.com/errata/RHSA-2015-0323.html
http://lists.opensuse.org/opensuse-updates/2015-01/msg00005.html
http://lists.opensuse.org/opensuse-updates/2015-01/msg00003.html
http://libvirt.org/git/?p=libvirt.git%3Ba=commit%3Bh=2bdcd29c713dfedd813c89f56ae98f6f3898313d