WordPress 2.1.1, as downloaded from some official distribution sites during February and March 2007, contains an externally introduced backdoor that allows remote attackers to execute arbitrary commands via (1) an eval injection vulnerability in the ix parameter to wp-includes/feed.php, and (2) an untrusted passthru call in the iz parameter to wp-includes/theme.php.
Improper Input Validation The product receives input or data, but it does
not validate or incorrectly validates that the input has the
properties that are required to process the data safely and
correctly.