MyBB (aka MyBulletinBoard) 1.4.3 includes the sensitive my_post_key parameter in URLs to moderation.php with the (1) mergeposts, (2) split, and (3) deleteposts actions, which allows remote attackers to steal the token and bypass the cross-site request forgery (CSRF) protection mechanism to hijack the authentication of moderators by reading the token from the HTTP Referer header.