WP Ultimate Review <= 2.4.3 - Unauthenticated Arbitrary Shortcode Execution via 'xs_reviw_summery' Parameter (Split-Shortcode / Late-Registered Shortcode)

The The WP Ultimate Review plugin for WordPress is vulnerable to arbitrary shortcode execution in all versions up to, and including, 2.4.3. This is due to the software allowing users to execute an action that does not properly validate a value before running do_shortcode. This makes it possible for unauthenticated attackers to execute arbitrary shortcodes. The nonce required to pass the only gate is emitted to unauthenticated visitors via the public review form, and submitted shortcode payloads are auto-published without admin approval by default, meaning exploitation requires no account and no privileged interaction.