The SearchIQ – The Search Solution plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the plugin's 'siq_searchbox' shortcode in all versions up to, and including, 4.6 due to insufficient input sanitization and output escaping on user supplied attributes. 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.
https://plugins.trac.wordpress.org/changeset/3198694/searchiq/trunk/library/shortcode.php
https://plugins.trac.wordpress.org/browser/searchiq/tags/4.6/library/shortcode.php#L66