django.contrib.sessions in Django before 1.2.7 and 1.3.x before 1.3.1, when session data is stored in the cache, uses the root namespace for both session identifiers and application-data keys, which allows remote attackers to modify a session by triggering use of a key that is equal to that session's identifier.
https://www.djangoproject.com/weblog/2011/sep/10/127/
https://www.djangoproject.com/weblog/2011/sep/09/
https://hermes.opensuse.org/messages/14700881
https://bugzilla.redhat.com/show_bug.cgi?id=737366
http://www.debian.org/security/2011/dsa-2332
http://secunia.com/advisories/46614