Minecraft Log4j Server Safety Guide

The Log4j vulnerability was one of the scarier security issues to hit Minecraft servers, mostly because the exploit could be triggered with something as simple as a line of text. Time has passed, many platforms have patched against it, but server owners should still understand what happened and what to check.

What Was the Log4j Issue?

Apache Log4j had a vulnerability that allowed attackers to run code remotely under certain conditions. For Minecraft servers, that created a serious risk: a malicious chat message could potentially lead to remote console access and the permissions attached to it.

Some server owners still report players joining, posting strange code-like strings in chat, and leaving immediately. Those attempts are usually automated scans looking for servers that were never secured.

Mojang's official notice about the vulnerability is available here.

Is a Minecraft Server Safe Now?

Servers running Minecraft 1.18.1 or newer are protected from this issue. If a server is on 1.18 or older, it may need extra startup protection through specific JVM arguments unless its software has already been patched.

To check or enable the needed startup option, use this general process:

1. Log in to your Minecraft control panel.
2. Open `Startup Parameters` from the left-side menu.
3. Enable the JVM argument needed for your version.
4. Restart the server.

If the JVM argument does not appear, restart the server and check again. If it still does not appear, open a support ticket. For 1.17 and newer servers, the correct argument may already be added automatically in the startup script, so it may not show as a manual option.

Patched Minecraft Server Software

The Minecraft server community responded quickly, and most common server builds received fixes. At the time the source article was written, the latest builds of these jars had been patched:

• Bungeecord
• Paper Waterfall
• CraftBukkit 1.18.1
• Fabric Loader
• Forge 1.18
• Forge 1.17.1
• Forge 1.16.5
• Forge 1.15.2
• Forge 1.14.4
• Forge 1.13.2
• Forge 1.12.2
• Paper 1.18.1
• Paper 1.18
• Paper 1.17.1
• Paper 1.16.5
• Paper 1.15.2
• Paper 1.14.4
• Paper 1.13.2
• Paper 1.12.2
• Paper 1.10.2
• Spigot 1.18.1
• Spigot 1.18
• Spigot 1.17.1
• Spigot 1.17
• Spigot 1.16.5
• Spigot 1.15.2
• Spigot 1.14.4
• Spigot 1.13.2
• Spigot 1.12.2
• Spigot 1.11.2
• Spigot 1.10.2
• Spigot 1.9.4
• Spigot 1.8.8
• Vanilla 1.7 to 1.18.1

If your server uses something outside that list, handle it carefully. Updating to 1.18.1 or newer is the safest route. If updating is not possible, apply Mojang's recommended fix for the affected version.

When to Ask for Help

If you are unsure whether your server is protected, ask support to verify it before opening the server publicly. Security guesswork is not a great hobby, and it is much less fun than actually playing Minecraft.