The XML libraries for Python 3.4, 3.3, 3.2, 3.1, 2.7, and 2.6, as used in OpenStack Keystone Essex, Folsom, and Grizzly; Compute (Nova) Essex and Folsom; Cinder Folsom; Django; and possibly other products allow remote attackers to cause a denial of service (resource consumption and crash) via an XML Entity Expansion (XEE) attack.