bugzilla_email_append.pl in Bugzilla 2.14.x before 2.14.4, and 2.16.x before 2.16.1, allows remote attackers to execute arbitrary code via shell metacharacters in a system call to processmail.
http://www.securityfocus.com/bid/5844
http://www.iss.net/security_center/static/10234.php