CVE 2016-3164
Drupal 6.x before 6.38, 7.x before 7.43, and 8.x before 8.0.4 might allow remote attackers to conduct open redirect attacks by leveraging (1) custom code or (2) a form shown on a 404 error page, related to path manipulation.
See the 
CVE page on Mitre.org
for more details.
