Related Posts for WordPress <= 2.2.1 - Cross-Site Request Forgery

The Related Posts for WordPress plugin for WordPress is vulnerable to Cross-Site Request Forgery in all versions up to, and including, 2.2.1. This is due to missing or incorrect nonce validation on the handle_create_link() function. This makes it possible for unauthenticated attackers to add related posts to other posts via a forged request granted they can trick a site administrator into performing an action such as clicking on a link. This ultimately makes it possible for attackers to view draft and password protected posts.