The Fluent Forms – Customizable Contact Forms, Survey, Quiz, & Conversational Form Builder plugin for WordPress is vulnerable to Reflected Cross-Site Scripting via 'param' in all versions up to, and including, 6.2.8 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.

The Fluent Forms WordPress plugin before 6.2.6 does not sanitise and escape one of its form field configuration settings before outputting it inside an inline script when a form is rendered, which could allow users with a role as low as Contributor (with delegated form-management permission, and therefore lacking the unfilteredhtml capability, e.g. in a multisite setup) to perform Stored Cross-Site Scripting attacks that execute in the browser of any visitor who loads the form, including administrators previewing it.

The Fluent Forms WordPress plugin before 6.2.1 does not properly verify ownership before processing a subscription cancellation request, allowing authenticated users with a low-privilege account to cancel subscriptions belonging to other users.