vars.php in WordPress 2.0.2, possibly when running on Mac OS X, allows remote attackers to spoof their IP address via a PC_REMOTE_ADDR HTTP header, which vars.php uses to redefine $_SERVER['REMOTE_ADDR'].
https://exchange.xforce.ibmcloud.com/vulnerabilities/26688
http://www.vupen.com/english/advisories/2006/1992
http://www.securityfocus.com/archive/1/435039/100/0/threaded