Input validation vulnerability in WP-Members Membership Plugin 3.4.9.5

The WP-Members Membership Plugin for WordPress has a security issue called Reflected Cross-Site Scripting. This is because it uses a feature called add_query_arg without properly protecting the URL. This vulnerability exists in all versions of the plugin up to and including 3.4.9.5. As a result, attackers who are not logged in can insert their own harmful scripts into web pages if they can convince a user to click on a certain link.