Update the WordPress Mantenimiento web plugin to the latest available version (at least 0.14).
Mika discovered and reported this Cross Site Scripting (XSS) vulnerability in WordPress Mantenimiento web Plugin. This could allow a malicious actor to inject malicious scripts, such as redirects, advertisements, and other HTML payloads into your website which will be executed when guests visit your site. This vulnerability has been fixed in version 0.14.
CrossSite Request Forgery (CSRF) vulnerability leading to Stored CrossSite Scripting (XSS)