Beaker before 1.6.4, when using PyCrypto to encrypt sessions, uses AES in ECB cipher mode, which might allow remote attackers to obtain portions of sensitive session data via unspecified vectors.
https://github.com/bbangert/beaker/commit/91becae76101cf87ce8cbfabe3af2622fc328fe5
https://bugzilla.redhat.com/show_bug.cgi?id=809267
http://www.openwall.com/lists/oss-security/2012/08/13/10
http://www.debian.org/security/2012/dsa-2541