Newsletter Email Subscribe <= 2.4 - Cross-Site Request Forgery to Plugin Settings Update

The Newsletter Email Subscribe plugin for WordPress is vulnerable to Cross-Site Request Forgery in versions up to, and including, 2.4. This is due to incorrect nonce validation on the nels_settings_page function. This makes it possible for unauthenticated attackers to update plugin settings via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.