We have released a hotfix that addresses a security-related concern raised to us by Unity. You can read more about the specific issue here: https://unity.com/security/sept-2025-01/
While the update patches out the flaw, Unity has said that, to their knowledge, no one has exploited the issue to date, and no players have been at risk.
To help ensure that this security flaw can never be exploited on Subnautica or Below Zero, we have updated Unity following the guidelines provided. We have also had to make the difficult decision to disable all legacy and alternative branches of Subnautica and Below Zero, as there is no way for us to patch out the security issue on each of those branches individually.
If you play Subnautica or Below Zero with any mods on our legacy or alternative branches, you should disable or remove them before launching the game after the update to preserve your save files. You will need to check that the mods you want to play are updated to work with the most recent version of the game.
For our speedrunning community, this also means that the speedrunners branch has been disabled. We understand that this will affect speedruns moving forward, but the security and safety of all our players is our highest priority.
Thank you for all your continued support for Subnautica and Below Zero!
Keep Diving.