ftpfile in the Vacation plugin 0.15 and earlier for Squirrelmail allows local users to execute arbitrary commands via shell metacharacters in a command line argument.
https://exchange.xforce.ibmcloud.com/vulnerabilities/18855
http://www.squirrelmail.org/plugin_view.php?id=51
http://www.securityfocus.com/bid/12222
http://securitytracker.com/id?1012866
http://security.lss.hr/en/index.php?page=details&ID=LSS-2005-01-03