Update the WordPress Shortcodes Ultimate plugin to the latest available version (at least 5.12.1).
Dave Jong discovered and reported this Cross Site Request Forgery (CSRF) vulnerability in WordPress Shortcodes Ultimate Plugin. This could allow a malicious actor to force higher privileged users to execute unwanted actions under their current authentication. For example a password change which will then allow the malicious actor to login into the admin account. This vulnerability has been fixed in version 5.12.1.
CSRF vulnerability leading to Stored XSS
Stored CrossSite Scripting (XSS) vulnerability