scripts/wwwacct in cPanel 11.18.6 STABLE and earlier and 11.23.1 CURRENT and earlier allows remote authenticated users with reseller privileges to execute arbitrary code via shell metacharacters in the Email address field (aka Email text box). NOTE: the vendor disputes this, stating "I'm unable to reproduce such an issue on multiple servers running different versions of cPanel.
https://exchange.xforce.ibmcloud.com/vulnerabilities/42529
http://www.securitytracker.com/id?1020042
http://www.securityfocus.com/archive/1/492259/100/0/threaded
http://www.securityfocus.com/archive/1/492223/100/0/threaded