Piracy: ꜱᴀɪʟ ᴛʜᴇ ʜɪɢʜ ꜱᴇᴀꜱ

https://github.com/jellyfin/jellyfin/issues/5415

The biggest issue is that the video stream endpoint is not auth'd. Meaning that if someone guesses the MD5 hash for a file in your library it will play. Sounds at first glance like it's unlikely to matter. Except that MD5 is generated based on the file's filepath. So if you use standard naming conventions on paths that are common (/movies/Big Bucks Bunny(2008)/Big Bucks Bunny.mkv for example being simple and easy), eg defaults for a docker container using *arr suites. Then it's possible for a precompiled hash list to check for file against your server.

So now add a company like Sony, they can generate all their library as a hash list, hit your server with millions of requests over the course of a couple of hours and map out how much of their content you have on your server. If any of it has never had a physical release (since you're allowed to backup your own content) you're completely fucked, and now will have to prove in court that you own ALL the content. And possibly... since it's open endpoint, it could be argued that you're even distributing openly (though unlikely argument... but do you really want to chance that?).

Ultimately if your setup is "Standard" you're asking for a lawsuit.

Answers to "fix" this:

Map your paths in weird folders. instead of /movies/ add in a folder like a GUID, so /eH4i67ZwByjLao3z7nHWKdS5ogysm68x/movies/. Make sure this occurs INSIDE your docker container if you're using docker. Will break any precompiled hashes... though possible to hit a collision and still be "found".

Setup fail2ban or other brute force blocking technology on your reverse proxy.

Use a private network setup... whether VPN, SDN, whatever... tailscale, zerotier, etc... (This will break TVs that don't have vpn capabilities)

Add another auth in front of Jellyfin. (This breaks ALL Jellyfin apps)

The real answer would be the developers closing the unauth endpoints... But it's been an issue for over 4 years now... They're not going to fix it anytime soon as they don't want to "break compatibility", which is a pretty dumb excuse IMO.

There's another issue where you shouldn't give accounts to people you don't trust as one user can attack another user AFTER login. So make sure you trust everyone you let have access... they can screw with your profile and do stuff you might not expect.