The System module in Drupal 6.x before 6.38 and 7.x before 7.43 might allow remote attackers to hijack the authentication of site administrators for requests that download and run files with arbitrary JSON-encoded content, aka a "reflected file download vulnerability."
https://www.drupal.org/SA-CORE-2016-001
http://www.openwall.com/lists/oss-security/2016/03/15/10