diff --git a/openair3/NAS/COMMON/ESM/MSG/PduSessionEstablishmentAccept.c b/openair3/NAS/COMMON/ESM/MSG/PduSessionEstablishmentAccept.c
index cbcd767c11..62d22698d7 100644
--- a/openair3/NAS/COMMON/ESM/MSG/PduSessionEstablishmentAccept.c
+++ b/openair3/NAS/COMMON/ESM/MSG/PduSessionEstablishmentAccept.c
@@ -167,17 +167,17 @@ void capture_pdu_session_establishment_accept_msg(uint8_t *buffer, uint32_t msg_
       case IEI_DNN:
         LOG_T(NAS, "PDU SESSION ESTABLISHMENT ACCEPT - Received DNN IE\n");
         psea_msg.dnn_ie.dnn_length = *(buffer + offset++);
-        uint8_t i=0;
-        char apn[20];
+        char apn[APN_MAX_LEN];
 
-        while (*(buffer + offset + i) != ASCII_ACK) {
-          apn[i] = *(buffer + offset + i);
-          ++i;
-        }
+        if(psea_msg.dnn_ie.dnn_length <= APN_MAX_LEN &&
+           psea_msg.dnn_ie.dnn_length >= APN_MIN_LEN) {
+          for (int i = 0 ; i < psea_msg.dnn_ie.dnn_length ; ++i)
+            apn[i] = *(buffer + offset + i);
+          LOG_T(NAS, "PDU SESSION ESTABLISHMENT ACCEPT - APN: %s\n", apn);
+        } else
+          LOG_E(NAS, "PDU SESSION ESTABLISHMENT ACCEPT - DNN IE has invalid length\n");
 
-        LOG_T(NAS, "PDU SESSION ESTABLISHMENT ACCEPT - APN: %s\n", apn);
-        offset += psea_msg.dnn_ie.dnn_length;
-        psea_iei = *(buffer + offset++);
+        offset = msg_length;
         break;
 
       default:
diff --git a/openair3/NAS/COMMON/ESM/MSG/PduSessionEstablishmentAccept.h b/openair3/NAS/COMMON/ESM/MSG/PduSessionEstablishmentAccept.h
index ca92e54418..0e09425033 100644
--- a/openair3/NAS/COMMON/ESM/MSG/PduSessionEstablishmentAccept.h
+++ b/openair3/NAS/COMMON/ESM/MSG/PduSessionEstablishmentAccept.h
@@ -54,9 +54,18 @@
 #define ROC_MODIFY_QOS_RULE_WITHOUT_PF  0b110 /* Modify existing QoS rule without modifying packet filters */
 #define ROC_RESERVED_1                  0b111 /* Reserved */
 
-/* DNN - ASCII Codes */
-
-#define ASCII_ACK 0x06 /* Delimiter in the DNN IEI */
+/* DNN - APN 
+ * TS 23.003 9.1
+ * The APN is composed of two parts, the APN Network Identifier (9.1.1) & The APN Operator Identifier (9.1.2).
+ * 
+ * The DNN information element has a length in the range of 3 to 102 octets.
+ * The Header is consisted of two octets, the DNN IEI and the Length of the DNN contents fields, each is 1 octet. 
+ * The DNN value payload starts from the 3rd octet.
+ * The accumulated max length of APN payload is 100 octets.
+ * The min length of the APN payload is 1 octet.
+ */
+#define APN_MAX_LEN 100
+#define APN_MIN_LEN 1
 
 /* Mandatory Presence IE - TS 24.501 Table 8.3.2.1.1 */