Sitekit <= 1.4 - Authenticated (Contributor+) Stored Cross-Site Scripting via 'sitekit_iframe' shortcode

The Sitekit plugin for WordPress is vulnerable to Stored Cross-Site Scripting via 'sitekit_iframe' shortcode in versions up to, and including, 1.4 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.