Retrieving files without a CID

Assuming we’ve added a file to ipfs, how would we retrieve the file if we no longer have access to the generated CID?

There is the concept of the Mutable File System where one could potentially list all files stored in a particular directory using human readable paths but using MFS means that you lose on the immutability guarantees of IPFS.

To summarize, is there a way one can “search” for files on IPFS using the API or retrieve files through a human readable path without losing on immutability?

– EDIT –
Additionally, if one stores a file on IPFS (assuming we’re using MFS) does that mean any node can tamper with the file and potentially remove/alter it?