The Ultimate Member – User Profile, Registration, Login, Member Directory, Content Restriction & Membership Plugin plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the user description field in all versions up to, and including, 2.11.1 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with subscriber level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. The vulnerability is only exploitable when "HTML support for user description" is enabled in Ultimate Member settings.