Electron Inc. Advanced Electron Forum before 1.0.7 allows remote attackers to execute arbitrary PHP code via PHP code embedded in bbcode in the email parameter, which is processed by the preg_replace function with the eval switch.
https://www.exploit-db.com/exploits/6499
https://exchange.xforce.ibmcloud.com/vulnerabilities/45270
http://www.securityfocus.com/archive/1/496552/100/0/threaded
http://www.gulftech.org/?node=research&article_id=00131-09202008
http://www.anelectron.com/board/index.php?tid=3282