diff --git a/src/core/thread/mle.cpp b/src/core/thread/mle.cpp
index 1df7d228e..50fdb0259 100644
--- a/src/core/thread/mle.cpp
+++ b/src/core/thread/mle.cpp
@@ -2750,18 +2750,6 @@ void Mle::HandleUdpReceive(Message &aMessage, const Ip6::MessageInfo &aMessageIn
 
         neighbor->SetMleFrameCounter(frameCounter + 1);
     }
-    else
-    {
-        if (!(command == Header::kCommandLinkRequest || command == Header::kCommandLinkAccept ||
-              command == Header::kCommandLinkAcceptAndRequest || command == Header::kCommandAdvertisement ||
-              command == Header::kCommandParentRequest || command == Header::kCommandParentResponse ||
-              command == Header::kCommandChildIdRequest || command == Header::kCommandChildUpdateRequest ||
-              command == Header::kCommandChildUpdateResponse || command == Header::kCommandAnnounce))
-        {
-            otLogDebgMle("mle sequence unknown! %d", command);
-            ExitNow();
-        }
-    }
 
     switch (command)
     {
@@ -2782,11 +2770,11 @@ void Mle::HandleUdpReceive(Message &aMessage, const Ip6::MessageInfo &aMessageIn
         break;
 
     case Header::kCommandDataRequest:
-        Get<MleRouter>().HandleDataRequest(aMessage, aMessageInfo);
+        Get<MleRouter>().HandleDataRequest(aMessage, aMessageInfo, neighbor);
         break;
 
     case Header::kCommandDataResponse:
-        HandleDataResponse(aMessage, aMessageInfo);
+        HandleDataResponse(aMessage, aMessageInfo, neighbor);
         break;
 
     case Header::kCommandParentRequest:
@@ -2802,7 +2790,7 @@ void Mle::HandleUdpReceive(Message &aMessage, const Ip6::MessageInfo &aMessageIn
         break;
 
     case Header::kCommandChildIdResponse:
-        HandleChildIdResponse(aMessage, aMessageInfo);
+        HandleChildIdResponse(aMessage, aMessageInfo, neighbor);
         break;
 
     case Header::kCommandChildUpdateRequest:
@@ -2835,7 +2823,7 @@ void Mle::HandleUdpReceive(Message &aMessage, const Ip6::MessageInfo &aMessageIn
 
 #if OPENTHREAD_CONFIG_TIME_SYNC_ENABLE
     case Header::kCommandTimeSync:
-        Get<MleRouter>().HandleTimeSync(aMessage, aMessageInfo);
+        Get<MleRouter>().HandleTimeSync(aMessage, aMessageInfo, neighbor);
         break;
 #endif
     }
@@ -2943,12 +2931,16 @@ exit:
     return error;
 }
 
-otError Mle::HandleDataResponse(const Message &aMessage, const Ip6::MessageInfo &aMessageInfo)
+otError Mle::HandleDataResponse(const Message &         aMessage,
+                                const Ip6::MessageInfo &aMessageInfo,
+                                const Neighbor *        aNeighbor)
 {
     otError error;
 
     LogMleMessage("Receive Data Response", aMessageInfo.GetPeerAddr());
 
+    VerifyOrExit(aNeighbor && aNeighbor->IsStateValid(), error = OT_ERROR_SECURITY);
+
     error = HandleLeaderData(aMessage, aMessageInfo);
 
     if (error != OT_ERROR_NONE)
@@ -2966,6 +2958,7 @@ otError Mle::HandleDataResponse(const Message &aMessage, const Ip6::MessageInfo
         IgnoreReturnValue(Get<DataPollSender>().StopFastPolls());
     }
 
+exit:
     return error;
 }
 
@@ -3383,7 +3376,9 @@ exit:
     return error;
 }
 
-otError Mle::HandleChildIdResponse(const Message &aMessage, const Ip6::MessageInfo &aMessageInfo)
+otError Mle::HandleChildIdResponse(const Message &         aMessage,
+                                   const Ip6::MessageInfo &aMessageInfo,
+                                   const Neighbor *        aNeighbor)
 {
     OT_UNUSED_VARIABLE(aMessageInfo);
 
@@ -3404,6 +3399,8 @@ otError Mle::HandleChildIdResponse(const Message &aMessage, const Ip6::MessageIn
 
     LogMleMessage("Receive Child ID Response", aMessageInfo.GetPeerAddr(), sourceAddress.GetRloc16());
 
+    VerifyOrExit(aNeighbor && aNeighbor->IsStateValid(), error = OT_ERROR_SECURITY);
+
     VerifyOrExit(mAttachState == kAttachStateChildIdRequest);
 
     // Leader Data
diff --git a/src/core/thread/mle.hpp b/src/core/thread/mle.hpp
index b20e0a7d6..7ab63742a 100644
--- a/src/core/thread/mle.hpp
+++ b/src/core/thread/mle.hpp
@@ -1707,14 +1707,18 @@ private:
     void        ScheduleMessageTransmissionTimer(void);
 
     otError HandleAdvertisement(const Message &aMessage, const Ip6::MessageInfo &aMessageInfo);
-    otError HandleChildIdResponse(const Message &aMessage, const Ip6::MessageInfo &aMessageInfo);
+    otError HandleChildIdResponse(const Message &         aMessage,
+                                  const Ip6::MessageInfo &aMessageInfo,
+                                  const Neighbor *        aNeighbor);
     otError HandleChildUpdateRequest(const Message &         aMessage,
                                      const Ip6::MessageInfo &aMessageInfo,
                                      Neighbor *              aNeighbor);
     otError HandleChildUpdateResponse(const Message &         aMessage,
                                       const Ip6::MessageInfo &aMessageInfo,
                                       const Neighbor *        aNeighbor);
-    otError HandleDataResponse(const Message &aMessage, const Ip6::MessageInfo &aMessageInfo);
+    otError HandleDataResponse(const Message &         aMessage,
+                               const Ip6::MessageInfo &aMessageInfo,
+                               const Neighbor *        aNeighbor);
     otError HandleParentResponse(const Message &aMessage, const Ip6::MessageInfo &aMessageInfo, uint32_t aKeySequence);
     otError HandleAnnounce(const Message &aMessage, const Ip6::MessageInfo &aMessageInfo);
     otError HandleDiscoveryResponse(const Message &aMessage, const Ip6::MessageInfo &aMessageInfo);
diff --git a/src/core/thread/mle_router.cpp b/src/core/thread/mle_router.cpp
index e22d6da4d..973202833 100644
--- a/src/core/thread/mle_router.cpp
+++ b/src/core/thread/mle_router.cpp
@@ -2483,7 +2483,9 @@ exit:
     return error;
 }
 
-otError MleRouter::HandleDataRequest(const Message &aMessage, const Ip6::MessageInfo &aMessageInfo)
+otError MleRouter::HandleDataRequest(const Message &         aMessage,
+                                     const Ip6::MessageInfo &aMessageInfo,
+                                     const Neighbor *        aNeighbor)
 {
     otError             error = OT_ERROR_NONE;
     TlvRequestTlv       tlvRequest;
@@ -2494,6 +2496,8 @@ otError MleRouter::HandleDataRequest(const Message &aMessage, const Ip6::Message
 
     LogMleMessage("Receive Data Request", aMessageInfo.GetPeerAddr());
 
+    VerifyOrExit(aNeighbor && aNeighbor->IsStateValid(), error = OT_ERROR_SECURITY);
+
     // TLV Request
     SuccessOrExit(error = Tlv::GetTlv(aMessage, Tlv::kTlvRequest, sizeof(tlvRequest), tlvRequest));
     VerifyOrExit(tlvRequest.IsValid() && tlvRequest.GetLength() <= sizeof(tlvs), error = OT_ERROR_PARSE);
@@ -4657,11 +4661,16 @@ bool MleRouter::IsSleepyChildSubscribed(const Ip6::Address &aAddress, Child &aCh
 }
 
 #if OPENTHREAD_CONFIG_TIME_SYNC_ENABLE
-void MleRouter::HandleTimeSync(const Message &aMessage, const Ip6::MessageInfo &aMessageInfo)
+void MleRouter::HandleTimeSync(const Message &aMessage, const Ip6::MessageInfo &aMessageInfo, const Neighbor *aNeighbor)
 {
     LogMleMessage("Receive Time Sync", aMessageInfo.GetPeerAddr());
 
+    VerifyOrExit(aNeighbor && aNeighbor->IsStateValid());
+
     Get<TimeSync>().HandleTimeSyncMessage(aMessage);
+
+exit:
+    return;
 }
 
 otError MleRouter::SendTimeSync(void)
diff --git a/src/core/thread/mle_router_ftd.hpp b/src/core/thread/mle_router_ftd.hpp
index 92794c13b..bb88a82ba 100644
--- a/src/core/thread/mle_router_ftd.hpp
+++ b/src/core/thread/mle_router_ftd.hpp
@@ -698,11 +698,11 @@ private:
                                       const Ip6::MessageInfo &aMessageInfo,
                                       uint32_t                aKeySequence,
                                       Neighbor *              aNeighbor);
-    otError HandleDataRequest(const Message &aMessage, const Ip6::MessageInfo &aMessageInfo);
+    otError HandleDataRequest(const Message &aMessage, const Ip6::MessageInfo &aMessageInfo, const Neighbor *aNeighbor);
     void    HandleNetworkDataUpdateRouter(void);
     otError HandleDiscoveryRequest(const Message &aMessage, const Ip6::MessageInfo &aMessageInfo);
 #if OPENTHREAD_CONFIG_TIME_SYNC_ENABLE
-    void HandleTimeSync(const Message &aMessage, const Ip6::MessageInfo &aMessageInfo);
+    void HandleTimeSync(const Message &aMessage, const Ip6::MessageInfo &aMessageInfo, const Neighbor *aNeighbor);
 #endif
 
     otError ProcessRouteTlv(const RouteTlv &aRoute);
diff --git a/src/core/thread/mle_router_mtd.hpp b/src/core/thread/mle_router_mtd.hpp
index aa4a3e067..9ca7bf68a 100644
--- a/src/core/thread/mle_router_mtd.hpp
+++ b/src/core/thread/mle_router_mtd.hpp
@@ -147,14 +147,14 @@ private:
     {
         return OT_ERROR_DROP;
     }
-    otError HandleDataRequest(const Message &, const Ip6::MessageInfo &) { return OT_ERROR_DROP; }
+    otError HandleDataRequest(const Message &, const Ip6::MessageInfo &, const Neighbor *) { return OT_ERROR_DROP; }
     void    HandleNetworkDataUpdateRouter(void) {}
     otError HandleDiscoveryRequest(const Message &, const Ip6::MessageInfo &) { return OT_ERROR_DROP; }
     void    HandlePartitionChange(void) {}
     void    StopAdvertiseTimer(void) {}
     otError ProcessRouteTlv(const RouteTlv &) { return OT_ERROR_NONE; }
 #if OPENTHREAD_CONFIG_TIME_SYNC_ENABLE
-    otError HandleTimeSync(const Message &, const Ip6::MessageInfo &) { return OT_ERROR_DROP; }
+    otError HandleTimeSync(const Message &, const Ip6::MessageInfo &, const Neighbor *) { return OT_ERROR_DROP; }
 #endif
 
     ChildTable  mChildTable;