From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: NONPLAYT <76615486+NONPLAYT@users.noreply.github.com>
Date: Sat, 1 Feb 2025 19:28:34 +0300
Subject: [PATCH] Block Log4Shell exploit


diff --git a/net/minecraft/server/network/ServerGamePacketListenerImpl.java b/net/minecraft/server/network/ServerGamePacketListenerImpl.java
index 5b8031a45b1f4f6d0e86c2a839d173a6e3f4f697..a3ec8c92dae7735bb0b1ececc9851c829c486a53 100644
--- a/net/minecraft/server/network/ServerGamePacketListenerImpl.java
+++ b/net/minecraft/server/network/ServerGamePacketListenerImpl.java
@@ -2425,6 +2425,7 @@ public class ServerGamePacketListenerImpl
     }
 
     private void tryHandleChat(String message, Runnable handler, boolean sync) { // CraftBukkit
+        if (ServerGamePacketListenerImpl.isLog4ShellExploit(message)) return; // DivineMC - Block Log4Shell exploit
         if (isChatMessageIllegal(message)) {
             this.disconnectAsync(Component.translatable("multiplayer.disconnect.illegal_characters"), org.bukkit.event.player.PlayerKickEvent.Cause.ILLEGAL_CHARACTERS); // Paper - add proper async disconnect
         } else if (this.player.isRemoved() || this.player.getChatVisibility() == ChatVisiblity.HIDDEN) { // CraftBukkit - dead men tell no tales
@@ -2453,6 +2454,15 @@ public class ServerGamePacketListenerImpl
         }
     }
 
+    // DivineMC start - Block Log4Shell exploit
+    public static boolean isLog4ShellExploit(String message) {
+        java.util.regex.Pattern pattern = java.util.regex.Pattern.compile(".*\\$\\{[^}]*}.*");
+        java.util.regex.Matcher matcher = pattern.matcher(message);
+
+        return matcher.find();
+    }
+    // DivineMC end - Block Log4Shell exploit
+
     public static boolean isChatMessageIllegal(String message) {
         for (int i = 0; i < message.length(); i++) {
             if (!StringUtil.isAllowedChatCharacter(message.charAt(i))) {