diff --git a/sdk/cosmos/azure-cosmos/CHANGELOG.md b/sdk/cosmos/azure-cosmos/CHANGELOG.md
index 9ac8342c42b7..6a5ba9e04600 100644
--- a/sdk/cosmos/azure-cosmos/CHANGELOG.md
+++ b/sdk/cosmos/azure-cosmos/CHANGELOG.md
@@ -11,6 +11,7 @@
 
 #### Other Changes
 * Replaced per-client `Schedulers.newSingle()` schedulers in `GlobalEndpointManager` and `GlobalPartitionEndpointManagerForPerPartitionCircuitBreaker` with shared `BoundedElastic` schedulers in `CosmosSchedulers` to prevent thread count from scaling linearly with client/tenant count. - See [PR 49062](https://github.com/Azure/azure-sdk-for-java/pull/49062)
+* Fixed a sporadic `NullPointerException` in `JsonSerializable.getWithMapping` triggered by concurrent first-time calls to `DatabaseAccount.getConsistencyPolicy()` and its sibling lazy getters (`getReplicationPolicy`, `getSystemReplicationPolicy`, `getQueryEngineConfiguration`). The fix makes `JsonSerializable.propertyBag` `final`, closing an unsafe-publication race in the lazy-initialisation pattern. - See [Issue 49256](https://github.com/Azure/azure-sdk-for-java/issues/49256) and [PR #49258](https://github.com/Azure/azure-sdk-for-java/pull/49258)
 
 ### 4.80.0 (2026-05-01)
 
diff --git a/sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/JsonSerializable.java b/sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/JsonSerializable.java
index c1ec176b8299..b955af019334 100644
--- a/sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/JsonSerializable.java
+++ b/sdk/cosmos/azure-cosmos/src/main/java/com/azure/cosmos/implementation/JsonSerializable.java
@@ -65,7 +65,7 @@ private static CosmosItemSerializer internalDefaultSerializer() {
 
     private static final ObjectMapper OBJECT_MAPPER= Utils.getSimpleObjectMapper();
     private static final Logger LOGGER = LoggerFactory.getLogger(JsonSerializable.class);
-    transient ObjectNode propertyBag = null;
+    final transient ObjectNode propertyBag;
     private ObjectMapper om;
 
     public JsonSerializable() {