An XSS issue was discovered in pfSense through 2.4.4-p3. In services_captiveportal_mac.php, the username and delmac parameters are displayed without sanitization.
https://www.seebug.org/vuldb/ssvid-98023
https://redmine.pfsense.org/issues/9609
https://github.com/pfsense/pfsense/commit/d31362b69d5d52dc196dc72f66e830cd1e6e9a4f