The Kubio AI Page Builder plugin for WordPress is vulnerable to Stored Cross-Site Scripting via kubio/copyright Block Content in all versions up to, and including, 2.8.4 due to insufficient input sanitization and output escaping. 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. This bypasses both the WordPress core kses-on-save filter and the plugin's own wp_kses_post() call, because entity-encoded script tags are treated as inert text by kses but are decoded into live HTML by the subsequent html_entity_decode() call in CopyrightBlock::render_template().