The WP ULike plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the plugin's 'wp_ulike' shortcode in all versions up to, and including, 4.6.9 due to insufficient input sanitization and output escaping on the user supplied 'wrapper_class' attribute. 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.