OpenStack Keystone token expiration issues

OpenStack Keystone before 2012.1.1, as used in OpenStack Folsom before Folsom-1 and OpenStack Essex, does not properly implement token expiration, which allows remote authenticated users to bypass intended authorization restrictions by (1) creating new tokens through token chaining, (2) leveraging possession of a token for a disabled user account, or (3) leveraging possession of a token for an account with a changed password.