A file upload vulnerability exists in Sourcecodester Engineers Online Portal in PHP via dashboard_teacher.php, which allows changing the avatar through teacher_avatar.php. Once an avatar gets uploaded it is getting uploaded to the /admin/uploads/ directory, and is accessible by all users. By uploading a php webshell containing "<?php system($_GET["cmd"]); ?>" the attacker can execute commands on the web server with - /admin/uploads/php-webshell?cmd=id.