diff --git a/os_stub/cryptlib_mbedtls/pk/x509.c b/os_stub/cryptlib_mbedtls/pk/x509.c
index e2120df66bc..afa85835799 100644
--- a/os_stub/cryptlib_mbedtls/pk/x509.c
+++ b/os_stub/cryptlib_mbedtls/pk/x509.c
@@ -1249,6 +1249,9 @@ bool libspdm_x509_get_extension_data(const uint8_t *cert, size_t cert_size,
 
     if (cert == NULL || cert_size == 0 || oid == NULL || oid_size == 0 ||
         extension_data_size == NULL) {
+        if (extension_data_size != NULL) {
+            *extension_data_size = 0;
+        }
         return false;
     }
 
@@ -1269,6 +1272,11 @@ bool libspdm_x509_get_extension_data(const uint8_t *cert, size_t cert_size,
     if (ret == 0) {
         status = libspdm_internal_x509_find_extension_data(
             ptr, end, oid, oid_size, &ptr, &obj_len);
+        if (!status) {
+            status = true;
+            *extension_data_size = 0;
+            goto cleanup;
+        }
     }
 
     if (status) {
diff --git a/os_stub/cryptlib_openssl/pk/x509.c b/os_stub/cryptlib_openssl/pk/x509.c
index 14bdc8504c7..c0803a6caf9 100644
--- a/os_stub/cryptlib_openssl/pk/x509.c
+++ b/os_stub/cryptlib_openssl/pk/x509.c
@@ -1351,22 +1351,23 @@ bool libspdm_x509_get_extension_data(const uint8_t *cert, size_t cert_size,
 
     if (cert == NULL || cert_size == 0 || oid == NULL || oid_size == 0 ||
         extension_data_size == NULL) {
+        if (extension_data_size != NULL) {
+            *extension_data_size = 0;
+        }
         return false;
     }
 
     x509_cert = NULL;
     status = false;
 
-
     /* Read DER-encoded X509 Certificate and Construct X509 object.*/
 
     status = libspdm_x509_construct_certificate(cert, cert_size, (uint8_t **)&x509_cert);
-    if ((x509_cert == NULL) || (!status)) {
+    if (!status) {
         *extension_data_size = 0;
         goto cleanup;
     }
 
-
     /* Retrieve extensions from certificate object.*/
 
     extensions = X509_get0_extensions(x509_cert);
@@ -1375,7 +1376,6 @@ bool libspdm_x509_get_extension_data(const uint8_t *cert, size_t cert_size,
         goto cleanup;
     }
 
-
     /* Traverse extensions*/
 
     status = false;
@@ -1410,6 +1410,7 @@ bool libspdm_x509_get_extension_data(const uint8_t *cert, size_t cert_size,
         /* reset to 0 if not found */
         oct_length = 0;
     }
+
     if (status) {
         if (*extension_data_size < oct_length) {
             *extension_data_size = oct_length;
@@ -1422,6 +1423,8 @@ bool libspdm_x509_get_extension_data(const uint8_t *cert, size_t cert_size,
         }
         *extension_data_size = oct_length;
     } else {
+        /* the cert extension is found, but the oid extension is not found; */
+        status = true;
         *extension_data_size = 0;
     }