The (1) contrib.sessions.backends.base.SessionBase.flush and (2) cache_db.SessionStore.flush functions in Django 1.7.x before 1.7.10, 1.4.x before 1.4.22, and possibly other versions create empty sessions in certain circumstances, which allows remote attackers to cause a denial of service (session store consumption) via unspecified vectors.
rhn.redhat.com/errata/RHSA-2015-1766.html
rhn.redhat.com/errata/RHSA-2015-1767.html
rhn.redhat.com/errata/RHSA-2015-1894.html
www.debian.org/security/2015/dsa-3338
www.oracle.com/technetwork/topics/security/bulletinoct2015-2511968.html
www.securityfocus.com/bid/76440
www.securitytracker.com/id/1033318
www.ubuntu.com/usn/USN-2720-1
lists.fedoraproject.org/pipermail/package-announce/2015-November/172084.html
www.djangoproject.com/weblog/2015/aug/18/security-releases/