CVE-2021-4421

The Advanced Popups plugin for WordPress is vulnerable to Cross-Site Request Forgery in versions up to, and including, 1.1.1. This is due to missing or incorrect nonce validation on the metabox_popup_save() function. This makes it possible for unauthenticated attackers to save meta tags via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.

Source: CVE-2021-4421