Minecraft 1.18.1-rc3
1.18.3-rc3 fixes a critical security issue. See the changelog.
Details
There are no changes other than the security fix. Mojang has also released a temporary fix in the launcher for versions 1.12+. To get the fix, stop any running instances of Minecraft and the launcher, then restart.
Do not play Minecraft on versions below 1.12 until further notice. Mojang has made an official announcement on the vulnerability. Read it before playing Minecraft or running a server.
Since there are still vulnerable Minecraft versions, I will not cover how the vulnerability works.
Edits
Dec 10 2021
- Added Mojang announcement