The Reviews Widgets for Google, Yelp & TripAdvisor plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'page_id' shortcode attribute of the [fbrev] shortcode in versions up to and including 2.7.3. This is due to insufficient input sanitization and output escaping in the Feed_Shortcode::fbrev() method, which passes the raw shortcode attribute through Feed_Old::get_feed() into the View::render() method, where it is echoed directly into the data-id HTML attribute without esc_attr(). This makes it possible for authenticated attackers, with contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.