OpenStack Identity (Keystone) before 2013.2.4, 2014.x before 2014.1.2, and Juno before Juno-2 allows remote authenticated trustees to gain access to an unauthorized project for which the trustor has certain roles via the project ID in a V2 API trust token request.
http://secunia.com/advisories/59426
http://lists.openstack.org/pipermail/openstack-announce/2014-July/000248.html