The Ultimate Member – User Profile, Registration, Login, Member Directory, Content Restriction & Membership Plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the YouTube Video 'value' field in all versions up to, and including, 2.11.0. This is due to insufficient input sanitization and output escaping on user-supplied YouTube video URLs in the `um_profile_field_filter_hook__youtube_video()` function. This makes it possible for authenticated attackers, with Subscriber-level access and above, to inject arbitrary web scripts in pages that execute whenever a user accesses the injected user's profile page.