diff --git a/common/serial/bytes.go b/common/serial/bytes.go
index a9295bcdb..ebbfa7591 100644
--- a/common/serial/bytes.go
+++ b/common/serial/bytes.go
@@ -10,6 +10,14 @@ func (this BytesLiteral) Value() []byte {
 	return []byte(this)
 }
 
+func (this BytesLiteral) Uint32Value() uint32 {
+	value := this.Value()
+	return uint32(value[0])<<24 +
+		uint32(value[1])<<16 +
+		uint32(value[2])<<8 +
+		uint32(value[3])
+}
+
 func (this BytesLiteral) Int64Value() int64 {
 	value := this.Value()
 	return int64(value[0])<<56 +
diff --git a/proxy/vmess/inbound/command.go b/proxy/vmess/inbound/command.go
index 8e713df11..bc2aa38b0 100644
--- a/proxy/vmess/inbound/command.go
+++ b/proxy/vmess/inbound/command.go
@@ -1,6 +1,8 @@
 package inbound
 
 import (
+	"hash/fnv"
+
 	"github.com/v2ray/v2ray-core/common/alloc"
 	"github.com/v2ray/v2ray-core/common/log"
 	"github.com/v2ray/v2ray-core/common/serial"
@@ -38,10 +40,14 @@ func (this *VMessInboundHandler) generateCommand(buffer *alloc.Buffer) {
 		}
 	}
 
-	if commandBytes.Len() > 256 {
+	if cmd == 0 || commandBytes.Len()+4 > 256 {
 		buffer.AppendBytes(byte(0), byte(0))
 	} else {
-		buffer.AppendBytes(cmd, byte(commandBytes.Len()))
+		buffer.AppendBytes(cmd, byte(commandBytes.Len()+4))
+		fnv1hash := fnv.New32a()
+		fnv1hash.Write(commandBytes.Value)
+		hashValue := fnv1hash.Sum32()
+		buffer.AppendBytes(byte(hashValue>>24), byte(hashValue>>16), byte(hashValue>>8), byte(hashValue))
 		buffer.Append(commandBytes.Value)
 	}
 }
diff --git a/proxy/vmess/outbound/command.go b/proxy/vmess/outbound/command.go
index 868f61a74..3f6bf5aca 100644
--- a/proxy/vmess/outbound/command.go
+++ b/proxy/vmess/outbound/command.go
@@ -1,8 +1,11 @@
 package outbound
 
 import (
+	"hash/fnv"
+
 	"github.com/v2ray/v2ray-core/common/log"
 	v2net "github.com/v2ray/v2ray-core/common/net"
+	"github.com/v2ray/v2ray-core/common/serial"
 	"github.com/v2ray/v2ray-core/proxy/vmess"
 	"github.com/v2ray/v2ray-core/proxy/vmess/command"
 )
@@ -14,6 +17,17 @@ func (this *VMessOutboundHandler) handleSwitchAccount(cmd *command.SwitchAccount
 }
 
 func (this *VMessOutboundHandler) handleCommand(dest v2net.Destination, cmdId byte, data []byte) {
+	if len(data) < 4 {
+		return
+	}
+	fnv1hash := fnv.New32a()
+	fnv1hash.Write(data[4:])
+	actualHashValue := fnv1hash.Sum32()
+	expectedHashValue := serial.BytesLiteral(data[:4]).Uint32Value()
+	if actualHashValue != expectedHashValue {
+		return
+	}
+	data = data[4:]
 	cmd, err := command.CreateResponseCommand(cmdId)
 	if err != nil {
 		log.Warning("VMessOut: Unknown response command (", cmdId, "): ", err)