Describe CVE-2011-4138.
What is CVE-2011-4138?
The verify_exists functionality in the URLField implementation in Django before 1.2.7 and 1.3.x before 1.3.1 originally tests a URL's validity through a HEAD request, but then uses a GET request for the new target URL in the case of a redirect, which might allow remote attackers to trigger arbitrary GET requests with an unintended source IP address via a crafted Location header..