ArCa Payment Gateway <= 1.3.1 - Cross-Site Request Forgery to Stored Cross-Site Scripting

The ArCa Payment Gateway plugin for WordPress is vulnerable to Cross-Site Request Forgery in all versions up to, and including, 1.3.1. This is due to missing or incorrect nonce validation on a function. 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.