FileUploadsFilter.php in X2Engine 4.1.7 and earlier, when running on case-insensitive file systems, allows remote attackers to bypass the u…

FileUploadsFilter.php in X2Engine 4.1.7 and earlier, when running on case-insensitive file systems, allows remote attackers to bypass the upload blacklist and conduct unrestricted file upload attacks by uploading a file with an executable extension that contains uppercase letters, as demonstrated using a PHP program.