The Responsive Blocks – WordPress Gutenberg Blocks plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the ‘section_tag’ parameter in all versions up to, and including, 1.9.9 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.