diff --git a/components/TARGET_PSA/services/attestation/COMPONENT_PSA_SRV_IMPL/attest_crypto.c b/components/TARGET_PSA/services/attestation/COMPONENT_PSA_SRV_IMPL/attest_crypto.c
index e1cb6d3619..3abe2a6354 100755
--- a/components/TARGET_PSA/services/attestation/COMPONENT_PSA_SRV_IMPL/attest_crypto.c
+++ b/components/TARGET_PSA/services/attestation/COMPONENT_PSA_SRV_IMPL/attest_crypto.c
@@ -208,6 +208,7 @@ t_cose_crypto_hash_start(struct t_cose_crypto_hash *hash_ctx,
     }
 
     psa_hash_ctx = (struct t_cose_psa_crypto_hash *)hash_ctx;
+    memset(&psa_hash_ctx->operation, 0, sizeof(psa_hash_operation_t));
 
     psa_ret = psa_hash_setup(&psa_hash_ctx->operation,
                              cose_hash_alg_id_to_psa(cose_hash_alg_id));
diff --git a/components/TARGET_PSA/services/attestation/COMPONENT_PSA_SRV_IMPL/attest_iat_claims_loader.c b/components/TARGET_PSA/services/attestation/COMPONENT_PSA_SRV_IMPL/attest_iat_claims_loader.c
index 80b40adde8..d7452668c7 100755
--- a/components/TARGET_PSA/services/attestation/COMPONENT_PSA_SRV_IMPL/attest_iat_claims_loader.c
+++ b/components/TARGET_PSA/services/attestation/COMPONENT_PSA_SRV_IMPL/attest_iat_claims_loader.c
@@ -70,7 +70,7 @@ static enum tfm_plat_err_t attest_public_key_sha256(uint32_t *size, uint8_t *buf
 
     psa_status_t crypto_ret;
     enum tfm_plat_err_t status = TFM_PLAT_ERR_SUCCESS;
-    psa_hash_operation_t hash_handle;
+    psa_hash_operation_t hash_handle = {0};
 
     crypto_ret = psa_open_key(PSA_KEY_LIFETIME_PERSISTENT, key_id, &handle);
     if (crypto_ret != PSA_SUCCESS) {
diff --git a/components/TARGET_PSA/services/attestation/COMPONENT_PSA_SRV_IMPL/tfm_impl/t_cose/src/t_cose_crypto.h b/components/TARGET_PSA/services/attestation/COMPONENT_PSA_SRV_IMPL/tfm_impl/t_cose/src/t_cose_crypto.h
index b77af32b92..ab4faac185 100644
--- a/components/TARGET_PSA/services/attestation/COMPONENT_PSA_SRV_IMPL/tfm_impl/t_cose/src/t_cose_crypto.h
+++ b/components/TARGET_PSA/services/attestation/COMPONENT_PSA_SRV_IMPL/tfm_impl/t_cose/src/t_cose_crypto.h
@@ -295,7 +295,7 @@ struct t_cose_crypto_hash {
      * actual hash implementation, so this is a fairly large and
      * accommodating size.
      */
-    uint8_t bytes[128];
+    uint8_t bytes[280];
 };