If guest has access to its hosting files, is that dangerous ?

[esmeralgan]

Because it may be convenient to store shared data of VM guests and real systems on one big partition, it may be also convenient to store the VM guests hosts files on that same partition.
So, suppose I run a VDI or raw partition guest system in Virtualbox, which has access to the files used by the host to run the guest, for example:
- through the vmdk partitions for a raw system
- through shared folder or vmdk disk for the VDI
Is that problematic ?
Are there basic principles about what to do and not to do ?

[socratis]

Is that problematic ?

If you mean that the host can get access to the VM's files and mess them up? Yes, by definition!

Are there basic principles about what to do and not to do ?

Don't!

There are no "principles", just common logic. Raw access is powerful, but it also means no brakes. You can do anything and everything you want, including screwing up your data. Irreversibly.