diff --git a/src/core/thread/mle.cpp b/src/core/thread/mle.cpp
index 413da2d5f..94268e3c1 100644
--- a/src/core/thread/mle.cpp
+++ b/src/core/thread/mle.cpp
@@ -3127,7 +3127,11 @@ void Mle::HandleParentResponse(RxInfo &aRxInfo)
 
 #if OPENTHREAD_CONFIG_MAC_CSL_RECEIVER_ENABLE
     // CSL Accuracy
-    if (Tlv::FindTlv(aRxInfo.mMessage, clockAccuracy) != kErrorNone)
+    if (Tlv::FindTlv(aRxInfo.mMessage, clockAccuracy) == kErrorNone)
+    {
+        VerifyOrExit(clockAccuracy.IsValid(), error = kErrorParse);
+    }
+    else
     {
         clockAccuracy.SetCslClockAccuracy(kCslWorstCrystalPpm);
         clockAccuracy.SetCslUncertainty(kCslWorstUncertainty);
@@ -3625,8 +3629,9 @@ void Mle::HandleChildUpdateResponse(RxInfo &aRxInfo)
 
 #if OPENTHREAD_CONFIG_MAC_CSL_RECEIVER_ENABLE
         // CSL Accuracy
-        if (Tlv::FindTlv(aRxInfo.mMessage, clockAccuracy) != kErrorNone)
+        if (Tlv::FindTlv(aRxInfo.mMessage, clockAccuracy) == kErrorNone)
         {
+            VerifyOrExit(clockAccuracy.IsValid(), error = kErrorParse);
             Get<Mac::Mac>().SetCslParentClockAccuracy(clockAccuracy.GetCslClockAccuracy());
             Get<Mac::Mac>().SetCslParentUncertainty(clockAccuracy.GetCslUncertainty());
         }
@@ -4808,27 +4813,27 @@ exit:
 
 Error Mle::TxMessage::AppendCslTimeoutTlv(void)
 {
-    OT_ASSERT(Get<Mac::Mac>().IsCslEnabled());
-    return Tlv::Append<CslTimeoutTlv>(*this,
-                                      Get<Mle>().mCslTimeout == 0 ? Get<Mle>().mTimeout : Get<Mle>().mCslTimeout);
+    uint32_t timeout = Get<Mle>().GetCslTimeout();
+
+    if (timeout == 0)
+    {
+        timeout = Get<Mle>().GetTimeout();
+    }
+
+    return Tlv::Append<CslTimeoutTlv>(*this, timeout);
 }
 #endif // OPENTHREAD_CONFIG_MAC_CSL_RECEIVER_ENABLE
 
 #if OPENTHREAD_CONFIG_MAC_CSL_TRANSMITTER_ENABLE
 Error Mle::TxMessage::AppendCslClockAccuracyTlv(void)
 {
-    Error               error = kErrorNone;
     CslClockAccuracyTlv cslClockAccuracy;
 
     cslClockAccuracy.Init();
-
     cslClockAccuracy.SetCslClockAccuracy(Get<Radio>().GetCslAccuracy());
     cslClockAccuracy.SetCslUncertainty(Get<Radio>().GetCslUncertainty());
 
-    SuccessOrExit(error = Append(cslClockAccuracy));
-
-exit:
-    return error;
+    return Append(cslClockAccuracy);
 }
 #endif
 
diff --git a/src/core/thread/mle_router.cpp b/src/core/thread/mle_router.cpp
index 06433ce32..ad1a42f6e 100644
--- a/src/core/thread/mle_router.cpp
+++ b/src/core/thread/mle_router.cpp
@@ -2647,15 +2647,22 @@ void MleRouter::HandleChildUpdateRequest(RxInfo &aRxInfo)
         CslChannelTlv cslChannel;
         uint32_t      cslTimeout;
 
-        if (Tlv::Find<CslTimeoutTlv>(aRxInfo.mMessage, cslTimeout) == kErrorNone)
+        switch (Tlv::Find<CslTimeoutTlv>(aRxInfo.mMessage, cslTimeout))
         {
+        case kErrorNone:
             child->SetCslTimeout(cslTimeout);
             // MUST include CSL accuracy TLV when request includes CSL timeout
             tlvs[tlvslength++] = Tlv::kCslClockAccuracy;
+            break;
+        case kErrorNotFound:
+            break;
+        default:
+            ExitNow(error = kErrorNone);
         }
 
         if (Tlv::FindTlv(aRxInfo.mMessage, cslChannel) == kErrorNone)
         {
+            VerifyOrExit(cslChannel.IsValid(), error = kErrorParse);
             child->SetCslChannel(static_cast<uint8_t>(cslChannel.GetChannel()));
         }
         else
diff --git a/src/core/thread/mle_tlvs.hpp b/src/core/thread/mle_tlvs.hpp
index 4b1dd6725..3e8e6ec51 100644
--- a/src/core/thread/mle_tlvs.hpp
+++ b/src/core/thread/mle_tlvs.hpp
@@ -1230,7 +1230,7 @@ public:
      * @retval FALSE  If the TLV does not appear to be well-formed.
      *
      */
-    bool IsValid(void) const { return GetLength() == sizeof(*this) - sizeof(Tlv); }
+    bool IsValid(void) const { return GetLength() >= sizeof(*this) - sizeof(Tlv); }
 
     /**
      * This method returns the Channel Page value.
@@ -1290,6 +1290,15 @@ public:
         SetLength(sizeof(*this) - sizeof(Tlv));
     }
 
+    /**
+     * This method indicates whether or not the TLV appears to be well-formed.
+     *
+     * @retval TRUE   If the TLV appears to be well-formed.
+     * @retval FALSE  If the TLV does not appear to be well-formed.
+     *
+     */
+    bool IsValid(void) const { return GetLength() >= sizeof(*this) - sizeof(Tlv); }
+
     /**
      * This method returns the CSL Clock Accuracy value.
      *