WP Count Down Timer <= 1.0.1 - Authenticated (Contributor+) Stored Cross-Site Scripting

The WP Count Down Timer plugin for WordPress is vulnerable to Stored Cross-Site Scripting via multiple parameters of the 'wp_countdown_timer' shortcode in all versions up to, and including, 1.0.1 due to insufficient input sanitization and output escaping. 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.