MyBB (aka MyBulletinBoard) before 1.4.12 does not properly restrict uid values for group join requests, which allows remote attackers to cause a denial of service (resource consumption) by using guest access to submit join request forms for moderated groups, related to usercp.php and managegroup.php.
SQL injection vulnerability in pages.php in Custom Pages 1.0 plugin for MyBulletinBoard (MyBB) allows remote attackers to execute arbitrary SQL commands via the page parameter.