OpenStack Identity Keystone is vulnerable to Block delegation escalation of privilege

OpenStack Identity (Keystone) before 2013.2.4, 2014.1 before 2014.1.2, and Juno before Juno-2 does not properly handle chained delegation, which allows remote authenticated users to gain privileges by leveraging a (1) trust or (2) OAuth token with impersonation enabled to create a new token with additional roles.