The Add Google +1 (Plus one) social share Button plugin for WordPress is vulnerable to Cross-Site Request Forgery in all versions up to, and including, 1.0.0. This is due to missing or incorrect nonce validation on the google-plus-one-share-button page. This makes it possible for unauthenticated attackers to update settings and inject malicious web scripts via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.