bindings: Internal entity expansion in Python XML libraries inflicts DoS vulnerabilities

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...