Simple Link Directory <= 8.9.2 - Authenticated (Contributor+) Stored Cross-Site Scripting via Shortcode Attributes

The Simple Link Directory plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the plugin's `qcopd-directory` shortcode in all versions up to, and including, 8.9.2. This is due to insufficient input sanitization and output escaping on user supplied attributes such as `title_font_size`. 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.