A JSON library in MyBB (aka MyBulletinBoard) before 1.8.4 allows remote attackers to obtain the installation path via unknown vectors.
http://www.securitytracker.com/id/1031953
http://www.securityfocus.com/bid/73216
http://blog.mybb.com/2015/02/15/mybb-1-8-4-released-feature-update-security-maintenance-release/