The WP Hallo Welt plugin for WordPress is vulnerable to Cross-Site Request Forgery in all versions up to, and including, 1.4. This is due to missing or incorrect nonce validation on the 'hallo_welt_seite' function. This makes it possible for unauthenticated attackers to update plugin 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. Due to the insufficient input sanitization and output escaping, this can lead to Stored Cross-Site Scripting.
CWE-352