OpenStack Dashboard (Horizon) before 2014.1.3 and 2014.2.x before 2014.2.1 does not properly handle session records when using a db or memcached session engine, which allows remote attackers to cause a denial of service via a large number of requests to the login page.
https://bugs.launchpad.net/horizon/+bug/1394370
http://www.oracle.com/technetwork/topics/security/bulletinjan2015-2370101.html
http://secunia.com/advisories/61186
http://lists.opensuse.org/opensuse-updates/2015-01/msg00040.html
http://lists.openstack.org/pipermail/openstack-announce/2014-December/000308.html
http://lists.fedoraproject.org/pipermail/package-announce/2015-January/147520.html