ATutor is vulnerable to Reflected XSS via popup parameter in preview.php. An authenticated attacker can inject a double quote into the popup parameter, break out of the attribute value, and append a new event handler such as onload. The related preview_top.php file sanitises these parameters, but that does not prevent XSS in the parent frameset rendered by preview.php itself.
Product is no longer actively supported and the vulnerabilities have not been fixed. Only version 2.2.4 was tested and confirmed as vulnerable, other versions were not tested but might also be vulnerable.