GUnet OpenEclass 1.7.3 E-learning platform - File Upload Extension Bypass

GUnet OpenEclass 1.7.3 allows authenticated users to bypass file extension restrictions when uploading files. By renaming a PHP file to .php3 or .PhP, an attacker can upload a web shell and execute arbitrary code on the server. This vulnerability enables remote code execution by bypassing the intended file type checks in the exercise submission feature.