The Groundhogg plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'gh_form' shortcode in versions up to, and including, 2.7.9.8 due to insufficient input sanitization and output escaping on user supplied attributes. This makes it possible for authenticated attackers with contributor-level and above permissions to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. Please note this only works with legacy contact forms.