diff --git a/NET Core/LibUA/LibUA.csproj b/NET Core/LibUA/LibUA.csproj
index bf876f1..603e641 100644
--- a/NET Core/LibUA/LibUA.csproj	
+++ b/NET Core/LibUA/LibUA.csproj	
@@ -10,7 +10,7 @@
     <Title>LibUA Core</Title>
     <RepositoryType>git</RepositoryType>
     <RepositoryUrl>https://github.com/nauful/libua</RepositoryUrl>
-    <Version>1.0.30</Version>
+    <Version>1.0.31</Version>
     <PackageReadmeFile>README.md</PackageReadmeFile>
     <PackageLicenseFile>LICENSE</PackageLicenseFile>
   </PropertyGroup>
diff --git a/NET Core/LibUA/NetDispatcher.cs b/NET Core/LibUA/NetDispatcher.cs
index aacaa21..c8be8c8 100644
--- a/NET Core/LibUA/NetDispatcher.cs	
+++ b/NET Core/LibUA/NetDispatcher.cs	
@@ -564,13 +564,22 @@ protected override int Consume(MemoryBuffer recvBuf)
                 }
                 else if (messageType == (uint)MessageType.Open)
                 {
+                    uint messageSize =
+                        (uint)recvBuf.Buffer[4] | (uint)(recvBuf.Buffer[5] << 8) |
+                        (uint)(recvBuf.Buffer[6] << 16) | (uint)(recvBuf.Buffer[7] << 24);
+
+                    if (messageSize > recvBuf.Capacity)
+                    {
+                        return 0;
+                    }
+
                     if (config.TL == null)
                     {
                         logger?.Log(LogLevel.Error, "{LoggerID}: Message type 0x{messageType:X} is not supported before Hello", LoggerID(), messageType);
                         return ErrorInternal;
                     }
 
-                    return DispatchOpen(config, recvBuf);
+                    return DispatchOpen(config, recvBuf.Duplicate((int)messageSize));
                 }
                 else if (messageType == (uint)MessageType.Message ||
                     messageType == (uint)MessageType.Close)
diff --git a/NET/LibUA/Client.cs b/NET/LibUA/Client.cs
index 7dab743..1efad42 100644
--- a/NET/LibUA/Client.cs
+++ b/NET/LibUA/Client.cs
@@ -1397,15 +1397,23 @@ private int Consume(SLChannel config, MemoryBuffer recvBuf)
             }
             else if (messageType == (uint)MessageType.Open)
             {
-                ManualResetEvent ev = null;
+                messageSize =
+                    (uint)recvBuf.Buffer[4] | (uint)(recvBuf.Buffer[5] << 8) |
+                    (uint)(recvBuf.Buffer[6] << 16) | (uint)(recvBuf.Buffer[7] << 24);
 
+                if (messageSize > recvBuf.Capacity)
+                {
+                    return 0;
+                }
+
+                ManualResetEvent ev = null;
                 lock (recvQueue)
                 {
                     var key = new Tuple<uint, uint>(messageType, 0);
                     recvQueue[key] = new RecvHandler()
                     {
                         Header = null,
-                        RecvBuf = recvBuf.Duplicate(),
+                        RecvBuf = recvBuf.Duplicate((int)messageSize),
                         Type = NodeId.Zero
                     };
 
diff --git a/NET/LibUA/MemoryBuffer.cs b/NET/LibUA/MemoryBuffer.cs
index 9b68b9d..0da92b9 100644
--- a/NET/LibUA/MemoryBuffer.cs
+++ b/NET/LibUA/MemoryBuffer.cs
@@ -766,6 +766,16 @@ public MemoryBuffer Duplicate()
 
                 return mb;
             }
+
+            public MemoryBuffer Duplicate(int TargetCapacity)
+            {
+                var mb = new MemoryBuffer(TargetCapacity);
+
+                mb.Append(Buffer, TargetCapacity);
+                mb.Position = Position;
+
+                return mb;
+            }
         }
     }
 }
diff --git a/NET/LibUA/NetDispatcher.cs b/NET/LibUA/NetDispatcher.cs
index a58e63a..19923b5 100644
--- a/NET/LibUA/NetDispatcher.cs
+++ b/NET/LibUA/NetDispatcher.cs
@@ -565,13 +565,22 @@ protected override int Consume(MemoryBuffer recvBuf)
                 }
                 else if (messageType == (uint)MessageType.Open)
                 {
+                    uint messageSize =
+                        (uint)recvBuf.Buffer[4] | (uint)(recvBuf.Buffer[5] << 8) |
+                        (uint)(recvBuf.Buffer[6] << 16) | (uint)(recvBuf.Buffer[7] << 24);
+
+                    if (messageSize > recvBuf.Capacity)
+                    {
+                        return 0;
+                    }
+
                     if (config.TL == null)
                     {
                         logger?.Log(LogLevel.Error, "{LoggerID}: Message type 0x{messageType:X} is not supported before Hello", LoggerID(), messageType);
                         return ErrorInternal;
                     }
 
-                    return DispatchOpen(config, recvBuf);
+                    return DispatchOpen(config, recvBuf.Duplicate((int)messageSize));
                 }
                 else if (messageType == (uint)MessageType.Message ||
                     messageType == (uint)MessageType.Close)
diff --git a/README.md b/README.md
index 4ac3c94..de3fba4 100644
--- a/README.md
+++ b/README.md
@@ -1,7 +1,7 @@
 # LibUA
 Open-source OPC UA client and server library for .NET Framework and .NET Core based on IEC 62541. Available a library, a demo client and a demo server. Tested and commercially used in industrial applications with commercial vendors' UA servers and clients.
 
-Available as a nuget package for .NET Core (1.0.30):
+Available as a nuget package for .NET Core (1.0.31):
 https://www.nuget.org/packages/nauful-LibUA-core
 
 ### Features