You'll need to update the Java Minecraft version immediately.
Microsoft had warned gamers on Friday that there was a serious security threat in the game. According to a Minecraft blog post, the vulnerability is caused by "an exploit within Log4j -- which is a common Java-based logging library."
All versions of the client have been updated to fix the issue. Players are advised to immediately update the game to keep their computers and servers safe.
Sometimes, the update can be downloaded automatically by restarting the game. For players who run their own servers, the instructions may be more thorough. The Minecraft blog has detailed instructions on how to fix it.
There are two versions of Minecraft, the popular building game. You can play the Bedrock version on mobile or console. Linux, macOS and Windows PC users can choose between the two versions. The Java version is intended for more serious players who wish to modify the game in their own way.
If you want to stay safe, consider using a minecraft server list.