DNS traffic can leak outside the VPN tunnel on Android

[Fibonacci]

DNS traffic can leak outside the VPN tunnel on Android

It is very easy to test this. Create a dummy wireguard profile and connect to it, of course you won’t have access to internet. But you will still be able to receive notifications from apps that uses Firebase. I just tested this right now on Android 14

So I made few tests about this.

This happens when I use the kernel module backend for wireguard.

As you can see in the screenshot, I’m connected to a dummy vpn, I don’t have internet access at all, but I still can receive Firebase push notifications.

This doesn’t happen when I use the userspace backend of wireguard.