The MetaMagic SEO Plugin plugin for WordPress is vulnerable to Cross-Site Request Forgery in all versions up to, and including, 1.6. This is due to missing or incorrect nonce validation on the metamagic_update_options function. This makes it possible for unauthenticated attackers to modify the plugin's SEO settings, including enabling or disabling the plugin and toggling description and keyword meta tag output via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.