JetFormBuilder < 3.6.5.2 - Unauthenticated Stored XSS via WYSIWYG Field in Notification Emails

Description

The plugin does not properly sanitise and escape a form field's value before including it in the HTML notification emails it sends, allowing unauthenticated users to inject arbitrary HTML into messages delivered to administrators and other recipients. Whether injected script executes depends on the recipient's mail client, but the injected markup is rendered regardless.