Drupal 6.x before 6.34 and 7.x before 7.34 allows remote attackers to hijack sessions via a crafted request, as demonstrated by a crafted request to a server that supports both HTTP and HTTPS sessions.
https://www.drupal.org/SA-CORE-2014-006
http://www.openwall.com/lists/oss-security/2014/11/20/3
http://www.openwall.com/lists/oss-security/2014/11/20/21
http://www.debian.org/security/2014/dsa-3075