From dacde328c9e2668dfef4954f499b89e0564a4af2 Mon Sep 17 00:00:00 2001
From: x86 <126331+x86@users.noreply.github.com>
Date: Sun, 8 Mar 2026 14:47:59 +1300
Subject: [PATCH] RCE Fix 4

---
 Minecraft.World/BlockRegionUpdatePacket.cpp | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/Minecraft.World/BlockRegionUpdatePacket.cpp b/Minecraft.World/BlockRegionUpdatePacket.cpp
index bec943d8d..afac43685 100644
--- a/Minecraft.World/BlockRegionUpdatePacket.cpp
+++ b/Minecraft.World/BlockRegionUpdatePacket.cpp
@@ -103,6 +103,12 @@ void BlockRegionUpdatePacket::read(DataInputStream *dis) //throws IOException
 	levelIdx = ( size >> 30 ) & 3;
 	size &= 0x3fffffff;
 
+	const int MAX_COMPRESSED_CHUNK_SIZE = 5 * 1024 * 1024;
+	if(size < 0 || size > MAX_COMPRESSED_CHUNK_SIZE)
+	{
+		size = 0;
+	}
+
 	if(size == 0)
 	{
 		buffer = byteArray();
@@ -131,7 +137,10 @@ void BlockRegionUpdatePacket::read(DataInputStream *dis) //throws IOException
 	
 
 		delete [] compressedBuffer.data;
-		assert(buffer.length == outputSize);
+		if(buffer.length != outputSize)
+		{
+			app.DebugPrintf("BlockRegionUpdatePacket: decompressed size mismatch (expected %d, got %d)\n", buffer.length, outputSize);
+		}
 	}
 }