The Inquiry Form to Posts or Pages plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'Form Header' field in versions up to and including 1.0. This is due to insufficient input sanitization when saving via update_option() and lack of output escaping when displaying the stored value. The vulnerability exists in two locations: (1) the plugin settings page at inq_form.php line 180 where the value is echoed into an HTML attribute without esc_attr(), and (2) the front-end shortcode output at inquery_form_to_posts_or_pages.php line 139 where the value is output in HTML content without esc_html(). This makes it possible for authenticated attackers with administrator-level access to inject arbitrary web scripts that will execute whenever a user accesses the plugin settings page or views a page containing the [inquiry_form] shortcode.