The memcache token backend in OpenStack Identity (Keystone) 2013.1 through 2.013.1.4, 2013.2 through 2013.2.2, and icehouse before icehouse-3, when issuing a trust token with impersonation enabled, does not include this token in the trustee's token-index-list, which prevents the token from being invalidated by bulk token revocation and allows the trustee to bypass intended access restrictions.