Ultimate Member WordPress plugin vulnerabilities

The Ultimate Member WordPress plugin before version 2.6.7 does not prevent visitors from creating user accounts with arbitrary capabilities, effectively allowing attackers to create administrator accounts at will.

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_url' parameter in all versions up to, and including, 2.14.0 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. Successful exploitation requires a visitor to click the attacker's Website URL link on their public Ultimate Member profile, a condition that is trivially met since the redirect-confirmation onclick handler is enabled by default on all new installations.

The Ultimate Member WordPress plugin before version 2.13.0 does not validate a submitted role selection when it cannot resolve the set of roles a profile form permits, and screens the value against the site's registered role names rather than against the form's own allow-list. This allows unauthenticated users who register through the plugin's own form to grant themselves arbitrary capabilities and reach administrator-equivalent access.

The Ultimate Member plugin for WordPress in versions up to and including 2.11.0 is vulnerable to Stored Cross-Site Scripting via the plugin's shortcode attributes due to insufficient input sanitization and output escaping. This allows authenticated attackers with Contributor-level access or higher to inject arbitrary web scripts into pages.