QR Twitter Widget <= 0.2.3 is vulnerable to Cross Site Scripting (XSS) vulnerability

The QR Twitter Widget plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the plugin's shortcode in versions up to, and including, 0.2.3 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.