The Remove Post Type Slug plugin for WordPress is vulnerable to Cross-Site Request Forgery in all versions up to, and including, 1.0.2. This is due to incorrect nonce validation logic that uses OR (||) instead of AND (&&), causing the validation to fail when the nonce field is not empty OR when verification fails, rather than when it's empty AND verification fails. This makes it possible for unauthenticated attackers to modify the plugin's post type slug removal settings via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.