PHPMailer 1.7, when configured to use sendmail, allows remote attackers to execute arbitrary shell commands via shell metacharacters in the SendmailSend function in class.phpmailer.php.
https://sourceforge.net/tracker/index.php?func=detail&aid=1734811&group_id=26031&atid=385707
https://exchange.xforce.ibmcloud.com/vulnerabilities/34818
http://yehg.net/lab/pr0js/advisories/%5BvTiger_5.2.1%5D_rce
http://www.vupen.com/english/advisories/2007/2267
http://www.vupen.com/english/advisories/2007/2161
http://www.securityfocus.com/bid/24417
http://www.securityfocus.com/archive/1/471065/100/0/threaded
http://www.debian.org/security/2007/dsa-1315
http://sourceforge.net/project/shownotes.php?release_id=517428&group_id=157374
http://securityreason.com/securityalert/2802
http://secunia.com/advisories/25758
http://secunia.com/advisories/25755
http://secunia.com/advisories/25626
http://seclists.org/fulldisclosure/2011/Oct/223
http://larholm.com/2007/06/11/phpmailer-0day-remote-execution/