No, Hibernate doesn't do anything to synchronize state of the entities in session cache with the DB, unless you request it explicitly.
Usually it's not a problem, because active work usually happens inside a transaction, and operations inside a transaction are not supposed to see changes made by other concurrent transactions (details depend on isolation level, though). So, behavior of Hibernate complements the typical semantics of transaction isolation in this case.
There can also be situations when state of the entity need to be explicitly synchronized to reflect changes made inside the same transaction. It may be caused by bulk update queries or execution of database triggers. In this case you need to request such a synchronization explicitly by calling refresh()
.