Currency Switcher for WooCommerce <= 2.16.2 - Reflected Cross-Site Scripting

The Currency Switcher for WooCommerce plugin for WordPress is vulnerable to Reflected Cross-Site Scripting due to the use of add_query_arg without appropriate escaping on the URL in all versions up to, and including, 2.16.2. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that execute if they can successfully trick a user into performing an action such as clicking on a link.

An issue was discovered in the Currency Switcher addon before 2.11.2 for WooCommerce if a user provides a currency that was not added by the administrator. In this case, even though the currency does not exist, it will be selected, but a price amount will fall back to the default currency. This means that if an attacker provides a currency that does not exist and is worth less than this default, the attacker can eventually purchase an item for a significantly cheaper price.