python-keystoneclient before 0.2.4, as used in OpenStack Keystone (Folsom), does not properly check expiry for PKI tokens, which allows remote authenticated users to (1) retain use of a token after it has expired, or (2) use a revoked token once it expires.
https://bugs.launchpad.net/python-keystoneclient/+bug/1179615
http://www.ubuntu.com/usn/USN-1875-1
http://www.ubuntu.com/usn/USN-1851-1
http://www.openwall.com/lists/oss-security/2013/05/28/7
http://rhn.redhat.com/errata/RHSA-2013-0944.html
http://lists.opensuse.org/opensuse-updates/2013-06/msg00198.html