It is certainly possible. You can write the files to anywhere that is accessible by the vcap user, which is the user that runs your app on Cloud Foundry. Please keep in mind though that the local file system exposed to your app is ephemeral. It will go away when your app has been restarted.
If you just need temporary storage of the files that you're uploading, then the ephemeral storage will likely work just fine. If you need persistent storage of the files then you cannot rely on the ephemeral storage and would need to ultimately put your files somewhere else like AWS S3 (or a compatible offering like Minio) or some other service.
Hope that helps!