The FormLift for Infusionsoft Web Forms plugin for WordPress is vulnerable to Missing Authorization in all versions up to, and including, 7.5.21. This is due to missing capability checks on the connect() and listen_for_tokens() methods of the FormLift_Infusionsoft_Manager class, both of which are hooked to 'plugins_loaded' and execute on every page load. The connect() function generates an OAuth connection password and leaks it in the redirect Location header without verifying the requesting user is authenticated or authorized. The listen_for_tokens() function only validates the temporary password but performs no user authentication before calling update_option() to save attacker-controlled OAuth tokens and app domain. This makes it possible for unauthenticated attackers to hijack the site's Infusionsoft connection by first triggering the OAuth flow to obtain the temporary password, then using that password to set arbitrary OAuth tokens and app domain via update_option(), effectively redirecting the plugin's API communication to an attacker-controlled server.