diff --git a/src/DataMapper/ResponseDataMapper/PosNetResponseDataMapper.php b/src/DataMapper/ResponseDataMapper/PosNetResponseDataMapper.php
index 1409e87e..9071f90f 100644
--- a/src/DataMapper/ResponseDataMapper/PosNetResponseDataMapper.php
+++ b/src/DataMapper/ResponseDataMapper/PosNetResponseDataMapper.php
@@ -89,15 +89,20 @@ public function map3DPaymentData(array $raw3DAuthResponseData, ?array $rawPaymen
         if (self::PROCEDURE_SUCCESS_CODE === $procReturnCode && $this->getStatusDetail($procReturnCode) === self::TX_APPROVED) {
             $status = self::TX_APPROVED;
         }
-        
-        /** @var array<string, string> $oosResolveMerchantDataResponse */
+
+        /** @var array<string, string|null> $oosResolveMerchantDataResponse */
         $oosResolveMerchantDataResponse = $raw3DAuthResponseData['oosResolveMerchantDataResponse'];
 
         $mdStatus = $oosResolveMerchantDataResponse['mdStatus'];
-
+        $transactionSecurity = null;
+        if (null === $mdStatus) {
+            $this->logger->error('mdStatus boş döndü. Sağlanan banka API bilgileri eksik/yanlış olabilir.');
+        } else {
+            $transactionSecurity = $this->mapResponseTransactionSecurity($mdStatus);
+        }
         $threeDResponse = [
             'order_id'             => $oosResolveMerchantDataResponse['xid'] ?? null,
-            'transaction_security' => $this->mapResponseTransactionSecurity($mdStatus),
+            'transaction_security' => $transactionSecurity,
             'proc_return_code'     => $procReturnCode,
             'status'               => $status,
             'status_detail'        => $this->getStatusDetail($procReturnCode),
@@ -156,7 +161,7 @@ public function mapCancelResponse($rawResponseData): array
         if (null !== $state) {
             $transactionType = $this->mapTxType($state);
         }
-        
+
         $results = [
             'auth_code'        => null,
             'trans_id'         => null,
@@ -222,7 +227,7 @@ public function mapStatusResponse(array $rawResponseData): array
         if (null !== $state) {
             $transactionType = $this->mapTxType($state);
         }
-        
+
         $results = [
             'auth_code'        => null,
             'trans_id'         => null,
@@ -269,7 +274,7 @@ public function mapHistoryResponse(array $rawResponseData): array
                     $state    = $transactionDetails[0]['state'];
                     $authCode = $transactionDetails[0]['authCode'];
                 }
-                
+
                 if (count($transactionDetails) > 1) {
                     foreach ($transactionDetails as $key => $_transaction) {
                         if ($key > 0) {
diff --git a/tests/DataMapper/ResponseDataMapper/PosNetResponseDataMapperTest.php b/tests/DataMapper/ResponseDataMapper/PosNetResponseDataMapperTest.php
index 0037e8c7..f2f0af63 100644
--- a/tests/DataMapper/ResponseDataMapper/PosNetResponseDataMapperTest.php
+++ b/tests/DataMapper/ResponseDataMapper/PosNetResponseDataMapperTest.php
@@ -236,6 +236,38 @@ public function threeDPaymentDataProvider(): array
                     'status_detail'        => null,
                 ],
             ],
+            'fail2-md-empty'    => [
+                // 3D Auth fail case
+                'threeDResponseData' => [
+                    'oosResolveMerchantDataResponse' => [
+                        'xid'            => 'YKB_0000080603153823',
+                        'amount'         => '5696',
+                        'currency'       => 'TL',
+                        'installment'    => '00',
+                        'point'          => '0',
+                        'pointAmount'    => '0',
+                        'txStatus'       => 'N',
+                        'mdStatus'       => '',
+                        'mdErrorMessage' => 'None 3D - Secure Transaction',
+                        'mac'            => 'ED7254A3ABC264QOP67MN',
+                    ],
+                ],
+                'paymentData'        => [],
+                'expectedData'       => [
+                    'transaction_security' => null,
+                    'md_status'            => null,
+                    'md_error_message'     => 'None 3D - Secure Transaction',
+                    'trans_id'             => null,
+                    'auth_code'            => null,
+                    'ref_ret_num'          => null,
+                    'error_code'           => null,
+                    'error_message'        => null,
+                    'order_id'             => 'YKB_0000080603153823',
+                    'proc_return_code'     => null,
+                    'status'               => 'declined',
+                    'status_detail'        => null,
+                ],
+            ],
         ];
     }