admin.php in PHP-Stats 0.1.9.1 and earlier allows remote attackers to bypass authentication, gain administrator privileges, and execute arbitrary PHP code by modifying the option[admin_pass] parameter and setting the pass_cookie to the MD5 hash of the specified password.
http://www.vupen.com/english/advisories/2006/0822
http://www.securityfocus.com/bid/16963
http://www.securityfocus.com/archive/1/429145/100/0/threaded
http://www.securityfocus.com/archive/1/428614/100/0/threaded
http://www.securityfocus.com/archive/1/426762/100/0/threaded