The Groundhogg plugin for Wordpress is vulnerable to Stored Cross-Site Scripting via the ‘label' parameter in versions up to, and including, 3.7.4.1 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with Administrator-level access, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. This only affects multi-site installations and installations where unfiltered_html has been disabled.
The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.