The V3 API in OpenStack Identity (Keystone) 2014.1.x before 2014.1.2.1 and Juno before Juno-3 updates the issued_at value for UUID v2 tokens, which allows remote authenticated users to bypass the token expiration and retain access via a verification (1) GET or (2) HEAD request to v3/auth/tokens/.
https://bugs.launchpad.net/keystone/+bug/1348820
http://www.ubuntu.com/usn/USN-2324-1
http://www.openwall.com/lists/oss-security/2014/08/15/6