Direct static code injection vulnerability in WordPress 2.0.2 and earlier allows remote attackers to execute arbitrary commands by inserting a carriage return and PHP code when updating a profile, which is appended after a special comment sequence into files in (1) wp-content/cache/userlogins/ (2) wp-content/cache/users/ which are later included by cache.php, as demonstrated using the displayname argument.
https://exchange.xforce.ibmcloud.com/vulnerabilities/26687
http://www.vupen.com/english/advisories/2006/1992
http://www.securityfocus.com/bid/18372
http://www.securityfocus.com/archive/1/435039/100/0/threaded
http://www.gentoo.org/security/en/glsa/glsa-200606-08.xml