Mullvad VPN through 2024.1 on Android does not set a DNS server in the blocking state (after a hard failure to create a tunnel), and thus DNS traffic can leave the device. Data showing that the affected device was the origin of sensitive DNS requests may be observed and logged by operators of unintended DNS servers.
The product establishes a communication channel to (or from) an endpoint for privileged or protected operations, but it does not properly ensure that it is communicating with the correct endpoint.
Attackers might be able to spoof the intended endpoint from a different system or process, thus gaining the same level of access as the intended endpoint. While this issue frequently involves authentication between network-based clients and servers, other types of communication channels and endpoints can have this weakness.