The django.util.http.is_safe_url function in Django before 1.4.18, 1.6.x before 1.6.10, and 1.7.x before 1.7.3 does not properly handle leading whitespaces, which allows remote attackers to conduct cross-site scripting (XSS) attacks via a crafted URL, related to redirect URLs, as demonstrated by a "\njavascript:" URL.
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.