The WP Data Access plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the Simple Form autocomplete lookup label in versions up to, and including, 5.5.89 This is due to insufficient output escaping on the value returned by WPDA_Autocomplete::autocomplete_lookup() when it is emitted into a single-quoted HTML attribute by WPDA_Simple_Form_Item_Autocomplete::show_item() (the escape-output lint is explicitly suppressed on the echo line). This makes it possible for authenticated attackers, with Subscriber-level access and above, who are permitted to edit a lookup row through a legacy Form, to inject arbitrary web scripts in pages that will execute whenever a user — including a higher-privileged user editing a linked record that uses the autocomplete relationship — accesses the injected page.