Lack of proper validation in immudb

Summary

immudb is a database with built-in cryptographic proof and verification. immudb client SDKs use server's UUID to distinguish between different server instance so that the client can connect to different immudb instances and keep the state for multiple servers. SDK does not validate this uuid and can accept any value reported by the server. A malicious server can change the reported UUID tricking the client to treat it as a different server thus accepting a state completely irrelevant to the one previously retrieved from the server. This issue has been patched in version 1.4.1. As a workaround, when initializing an immudb client object a custom state handler can be used to store the state. Providing custom implementation that ignores the server UUID can be used to ensure that even if the server changes the UUID, client will still consider it to be the same server.