Authentication bypass in FalkorDB Bolt endpoint via fail-open AUTH probe error handling

An improper authentication vulnerability in the is_authenticated function (src/bolt/bolt_api.c) in FalkorDB before 4.20.0 allows a remote unauthenticated attacker to execute graph queries without credentials through the Bolt endpoint. The function decides whether a password is required by issuing an empty AUTH command to Redis and treats only a WRONGPASS error as meaning that a password is required; any other error, such as LOADING while a dataset is being loaded, MASTERDOWN during replication failover, or OOM under memory pressure, causes the client to be treated as authenticated. Only deployments that enable the Bolt endpoint (BOLT_PORT, disabled by default) are affected.