WPML Multilingual CMS 3.6.0 - 4.7.3 - Authenticated (Contributor+) Stored Cross-Site Scripting via wpml_language_switcher Shortcode

The WPML plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the plugin's wpml_language_switcher shortcode in versions 3.6.0 - 4.7.3 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.