Just leaving this here

Now, let’s address this clearly once and for all. What is possible is unauthenticated streaming. Each item in a Jellyfin library has a UUID generated which is based on a checksum of the file path. So, theoretically, if someone knows your exact media paths, they could calculate the item IDs, and then use that ItemID to initiate an unauthenticated stream of the media. As far as we know this has never actually been seen in the wild. This does not affect anything else - all other configuration/management endpoints are behind user authentication. Is this suboptimal? Yes. Is this a massive red-flag security risk that actively exposes your data to the Internet? No.

https://github.com/jellyfin/jellyfin/issues/5415#issuecomment-2825240290