CVE 2015-0219
Django before 1.4.18, 1.6.x before 1.6.10, and 1.7.x before 1.7.3 allows remote attackers to spoof WSGI headers by using an _ (underscore) character instead of a - (dash) character in an HTTP header, as demonstrated by an X-Auth_User header.
See the 
CVE page on Mitre.org
for more details.
