member.php in MyBB (aka MyBulletinBoard), when debug mode is available, allows remote authenticated users to change the password of any account by providing the account's registered e-mail address in a debug request for a do_lostpw action, which prints the change password verification code in the debug output.
https://exchange.xforce.ibmcloud.com/vulnerabilities/33345
http://www.securityfocus.com/archive/1/464267/100/100/threaded