The Dideo plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the plugin's 'dideo' shortcode in version 1.0. This is due to insufficient input sanitization and output escaping on the 'id' shortcode attribute, which is interpolated directly into an HTML iframe 'src' attribute without escaping in the dideo() shortcode handler. 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.