OpenStack Compute (nova) before 2014.2.4 (juno) and 2015.1.x before 2015.1.2 (kilo) does not properly delete instances from compute nodes, which allows remote authenticated users to cause a denial of service (disk consumption) by deleting instances while in the resize state.
https://security.openstack.org/ossa/OSSA-2015-017.html
https://launchpad.net/bugs/1392527
http://www.securityfocus.com/bid/76553
http://www.oracle.com/technetwork/topics/security/bulletinjan2016-2867206.html