Laravel 5 (L5): In my project in, when I return image (file) and want to avoid CORS i use following code (I change it a little by hand without testing but it should work):

private function responseFile($filePath, $fileMimeType,  $originalFileName) {

    $headers = array(
        'Content-Type' => $fileMimeType,
        //'Content-Disposition' => 'attachment; filename="'. $attachment->org_name . '"', - this header is added automaticaly
        "Access-Control-Allow-Origin" => request()->getSchemeAndHttpHost() // allow CORS (e.g. for images)
    );

    return response()->download($filePath, $originalFileName, $headers);
}

In this solution you don't need to touch apache .htaccess file (or nginx config files) at all (if you do it it will cause errors with headers duplication) - because in this case we use so called Simple CORS request.

You can also read this answer to avoid other problems which can cause that CORS error.

Try these methods:

1. Install and config Cors from enter link description here
2. Add Cors mode

fetch(url,{mode:"cors"})
                    .then(res => res.blob())
                    .then(blob => {
                        const file = new File([blob], 'dot.png', {type:'image/png'});
                        console.log(file);
                    });

3. Resource from enter link description here