diff --git a/services/implementation/src/attest/dm_auth_attest_common.cpp b/services/implementation/src/attest/dm_auth_attest_common.cpp
index 50a43b60af2ceefb13bc0c9bc0628d0de1ce50c9..deec44d104da7dbf1b33900e0ca72c217b676770 100644
--- a/services/implementation/src/attest/dm_auth_attest_common.cpp
+++ b/services/implementation/src/attest/dm_auth_attest_common.cpp
@@ -23,6 +23,7 @@ namespace DistributedHardware {
 
 const int32_t MAX_CERT_COUNT = 100;
 constexpr int32_t HEX_TO_UINT8 = 2;
+const int32_t MAX_LEN_PER_CERT = 8192;
 
 AuthAttestCommon::AuthAttestCommon()
 {
@@ -45,8 +46,8 @@ std::string AuthAttestCommon::SerializeDmCertChain(const DmCertChain *chain)
     JsonObject jsonArrayObj(JsonCreateType::JSON_CREATE_TYPE_ARRAY);
     for (uint32_t i = 0; i < chain->certCount; ++i) {
         const DmBlob &blob = chain->cert[i];
-        if (blob.data == nullptr || blob.size == 0) {
-            LOGE("blob data or size is empty.");
+        if (blob.data == nullptr || blob.size == 0 || blob.size > MAX_LEN_PER_CERT) {
+            LOGE("Invalid blob: null data or invalid size.");
             return "{}";
         }
         const uint32_t hexLen = blob.size * HEX_TO_UINT8 + 1; // 2*blob.size + 1
diff --git a/services/service/src/hichain/hichain_listener.cpp b/services/service/src/hichain/hichain_listener.cpp
index b6ffdedb7c65c9f5bc6c089cbf7d9663f06ae68e..1779410c6d9a709ab748459cc7ceb087e551ff10 100644
--- a/services/service/src/hichain/hichain_listener.cpp
+++ b/services/service/src/hichain/hichain_listener.cpp
@@ -186,7 +186,7 @@ void HichainListener::OnCredentialDeleted(const char *credId, const char *credIn
     uint32_t credType = 0;
     std::string credTypeTag = "credType";
     if (IsInt32(jsonObject, credTypeTag)) {
-        credType = jsonObject[credTypeTag].Get<int32_t>();
+        credType = static_cast<uint32_t>(jsonObject[credTypeTag].Get<int32_t>());
     }
     if (credType != ACCOUNT_SHARED) {
         LOGE("credType %{public}d is invalid.", credType);