MyBB (aka MyBulletinBoard) before 1.6.7 allows remote attackers to obtain sensitive information via a malformed forumread cookie, which reveals the installation path in an error message.
http://www.securityfocus.com/bid/53417
http://www.openwall.com/lists/oss-security/2012/05/07/14
http://www.openwall.com/lists/oss-security/2012/05/07/13
http://blog.mybb.com/2012/04/01/mybb-1-6-7-update-1-8-development/