The ewirePC_Decrypt function in ewirepcfunctions.php in eWire Payment Client (ePC) 1.60 and 1.70 allows remote attackers to execute arbitrary commands via shell metacharacters in the paymentinfo parameter to simplePHPLinux/3payment_receive.php.
http://www.vupen.com/english/advisories/2007/3183
http://www.securityfocus.com/bid/25683
http://www.fortconsult.net/images/pdf/advisory_feb2007.pdf