The WP ULike plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the `[wp_ulike_likers_box]` shortcode `template` attribute in all versions up to, and including, 5.0.1. This is due to the use of `html_entity_decode()` on shortcode attributes without subsequent output sanitization, which effectively bypasses WordPress's `wp_kses_post()` content filtering. 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. The post must have at least one like for the XSS to render.
https://plugins.trac.wordpress.org/browser/wp-ulike/trunk/includes/hooks/shortcodes.php#L209
https://plugins.trac.wordpress.org/browser/wp-ulike/trunk/includes/functions/utilities.php#L251
https://plugins.trac.wordpress.org/browser/wp-ulike/trunk/includes/functions/utilities.php#L226
https://plugins.trac.wordpress.org/browser/wp-ulike/trunk/includes/functions/general.php#L375
https://github.com/Alimir/wp-ulike/commit/3dcce696ea251b3733448332cc167e03b2a17c12