CORS issues, image is uploading but not inserting into editor

Question

My frontend (react) is at 8001 port and serverside(laravel) at 8000. I've installed elfinder in laravel and CkEditor 4 in react. Integrating elfinder with Ckeditor is done, uploading works correct, but when trying to insert an image to ckeditor error is occured

Error in getFileCallback.
Blocked a frame with origin "http://localhost:8000" from accessing a cross-origin frame.

Trying with CustomCors in laravel doesn't work.

<?php    
namespace App\Http\Middleware;    
use Closure;    
class CustomCors
{
    public function handle($request, Closure $next)
    {
        $response = $next($request);    
        $response->headers->set('Access-Control-Allow-Origin', 'http://localhost:8001'); // Set your frontend URL here
        $response->headers->set('Access-Control-Allow-Methods', 'GET, POST, PUT, DELETE, OPTIONS');
        $response->headers->set('Access-Control-Allow-Headers', 'Content-Type, Authorization');    
        return $response;
    }
}

I think CORS is related to CkEditor instead of elfinder and Laravel.