The ZT Captcha plugin for WordPress is vulnerable to Cross-Site Request Forgery in all versions up to, and including, 1.0.4. This is due to improper nonce validation on the save_ztcpt_captcha_settings action where the nonce check can be bypassed by sending an empty token value. This makes it possible for unauthenticated attackers to modify the plugin's settings via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.