The client in Northern.tech Mender 3.2.0, 3.2.1, and 3.2.2 has Incorrect Access Control.

Summary

The client in Northern.tech Mender 3.2.0, 3.2.1, and 3.2.2 has Incorrect Access Control. It listens on a random, unprivileged TCP port and exposes an HTTP proxy to facilitate API calls from additional client components running on the device. However, it listens on all network interfaces instead of only the localhost interface. Therefore, any client on the same network can connect to this TCP port and send HTTP requests. The Mender Client will forward these requests to the Mender Server. Additionally, if mTLS is set up, the Mender Client will connect to the Mender Server using the device's client certificate, making it possible for the attacker to bypass mTLS authentication and send requests to the Mender Server without direct access to the client certificate and related private key. Accessing the HTTP proxy from the local network doesn't represent a direct threat, because it doesn't expose any device or server-specific data. However, it increases the attack surface and can be a potential vector to exploit other vulnerabilities both on the Client and the Server.