The ER Swiffy Insert plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the [swiffy] shortcode in all versions up to and including 1.0.0. This is due to insufficient input sanitization and output escaping on user-supplied shortcode attributes ('n', 'w', 'h'). These attributes are extracted using extract() and directly interpolated into the HTML output without any escaping such as esc_attr(). 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.