The Purchase Button For Affiliate Link plugin for WordPress is vulnerable to Cross-Site Request Forgery in all versions up to, and including, 1.0.2. This is due to missing nonce validation on the settings page form handler in `inc/purchase-btn-options-page.php`. This makes it possible for unauthenticated attackers to modify plugin settings via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.