The Delete Custom Fields plugin for WordPress is vulnerable to Cross-Site Request Forgery in all versions up to, and including, 0.3.1. This is due to missing or incorrect nonce validation on the ajax_delete_field() function. This makes it possible for unauthenticated malicious users to delete arbitrary post meta data via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.
Vulmon