WPForms <= 2.0.2.1 - Reflected Cross-Site Scripting via 'query_var' Smart Tag in iframe srcdoc Attribute

The WPForms – AI Form Builder for WordPress – Contact Forms, Payment Forms, Survey Form, Quiz & More plugin for WordPress is vulnerable to Reflected Cross-Site Scripting via the 'attacker-chosen key referenced by the smart tag (e.g. "x")' parameter in all versions up to, and including, 2.0.2.1 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that execute if they can successfully trick a user into performing an action such as clicking on a link. Exploitation requires that a site administrator has previously saved a form whose description embeds a {query_var} Smart Tag inside an iframe srcdoc attribute and has enabled Show Description on a public-facing page.