Multiple cross-site scripting (XSS) vulnerabilities in the MyBB (aka MyBulletinBoard) before 1.8.4 allow remote authenticated users to inject arbitrary web script or HTML via the title parameter in the (1) edit or (2) add action in the user-users module or the (3) finduser action or the name parameter in an (4) edit action in the user-user module or the (5) editprofile action to modcp.php.
https://adamziaja.com/poc/201312-xss-mybb.html
http://blog.mybb.com/2015/02/15/mybb-1-8-4-released-feature-update-security-maintenance-release/