The Premmerce plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'premmerce_wizard_actions' AJAX endpoint in all versions up to, and including, 1.3.20. This is due to missing capability checks and insufficient input sanitization and output escaping on the state parameter. This makes it possible for authenticated attackers, with subscriber level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page (the Premmerce Wizard admin page).