The virDomainListPopulate function in conf/domain_conf.c in libvirt before 1.2.9 does not clean up the lock on the list of domains, which allows remote attackers to cause a denial of service (deadlock) via a NULL value in the second parameter in the virConnectListAllDomains API command.
http://libvirt.org/git/?p=libvirt.git;a=commitdiff;h=fc22b2e74890873848b43fffae43025d22053669
http://lists.opensuse.org/opensuse-updates/2014-10/msg00014.html
http://lists.opensuse.org/opensuse-updates/2014-10/msg00017.html
http://rhn.redhat.com/errata/RHSA-2014-1352.html
http://secunia.com/advisories/60291
http://secunia.com/advisories/62303