The password reset feature in PunBB 1.2.16 and earlier uses predictable random numbers based on the system time, which allows remote authenticated users to determine the new password via a brute force attack on a seed that is based on the approximate creation time of the targeted account. NOTE: this issue might be related to CVE-2006-5737.
https://www.exploit-db.com/exploits/5165
http://www.securityfocus.com/bid/27908
http://www.securityfocus.com/archive/1/488408/100/200/threaded
http://sektioneins.de/advisories/SE-2008-01.txt
http://secunia.com/advisories/29043
http://punbb.org/forums/viewtopic.php?id=18460