Cross-site scripting (XSS) vulnerability in the Max Foundry MaxButtons plugin before 1.26.1 for WordPress allows remote attackers to inject arbitrary web script or HTML via the id parameter in a button action on the maxbuttons-controller page to wp-admin/admin.php, related to the button creation page.
https://www.htbridge.com/advisory/HTB23237
https://wordpress.org/plugins/maxbuttons/changelog
http://www.securityfocus.com/archive/1/533700/100/0/threaded