OpenStack Keystone 2012.1.3 does not invalidate existing tokens when granting or revoking roles, which allows remote authenticated users to retain the privileges of the revoked roles.
https://exchange.xforce.ibmcloud.com/vulnerabilities/78478
http://www.ubuntu.com/usn/USN-1564-1
http://www.securityfocus.com/bid/55524
http://www.openwall.com/lists/oss-security/2012/09/12/7
http://secunia.com/advisories/50590