Django before 1.4.21, 1.5.x through 1.6.x, 1.7.x before 1.7.9, and 1.8.x before 1.8.3 uses an incorrect regular expression, which allows remote attackers to inject arbitrary headers and conduct HTTP response splitting attacks via a newline character in an (1) email message to the EmailValidator, a (2) URL to the URLValidator, or unspecified vectors to the (3) validate_ipv4_address or (4) validate_slug validator.
https://www.djangoproject.com/weblog/2015/jul/08/security-releases/
https://security.gentoo.org/glsa/201510-06
http://www.ubuntu.com/usn/USN-2671-1
http://www.securitytracker.com/id/1032820
http://www.securityfocus.com/bid/75665
http://www.oracle.com/technetwork/topics/security/bulletinoct2015-2511968.html
http://www.debian.org/security/2015/dsa-3305
http://lists.opensuse.org/opensuse-updates/2015-10/msg00046.html
http://lists.opensuse.org/opensuse-updates/2015-10/msg00043.html
http://lists.fedoraproject.org/pipermail/package-announce/2015-November/172084.html