In the Active Threads Plugin 1.3.0 for MyBB, the activethreads.php date parameter is vulnerable to XSS when setting a time period.
https://community.mybb.com/mods.php?action=view&pid=1336
http://packetstormsecurity.com/files/171402/MyBB-Active-Threads-1.3.0-Cross-Site-Scripting.html