diff --git a/src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/OtOpcUaNodeManager.cs b/src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/OtOpcUaNodeManager.cs
index ecbdc79c..ed397b0a 100644
--- a/src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/OtOpcUaNodeManager.cs
+++ b/src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/OtOpcUaNodeManager.cs
@@ -2877,9 +2877,15 @@ public sealed class OtOpcUaNodeManager : CustomNodeManager2
         IEventMonitoredItem monitoredItem,
         bool unsubscribe)
     {
+        // ⚠️ sourceId is the MANAGER HANDLE, not a NodeState — the same `object`-typed trap as
+        // ContinuationPoint.NodeToBrowse. Casting it to NodeState compiles, always yields null, and
+        // silently disables this gate; IsHandleInNamespace is the SDK's own resolver and cannot be
+        // wrong about it.
+        //
         // Only creation is gated. Refusing an UNSUBSCRIBE would strand the item on a node the session can
         // no longer reach — the client could never detach it, and the server would keep delivering.
-        if (AclEnforced && !unsubscribe && sourceId is NodeState source
+        if (AclEnforced && !unsubscribe
+            && IsHandleInNamespace(sourceId) is { } source
             && !Permits(IdentityOf(context), OpcUaOperation.CreateMonitoredItems, source.NodeId))
         {
             return StatusCodes.BadUserAccessDenied;
diff --git a/tests/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer.Tests/NodeManagerStage6EnforcementTests.cs b/tests/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer.Tests/NodeManagerStage6EnforcementTests.cs
index 9c4256b2..595c677f 100644
--- a/tests/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer.Tests/NodeManagerStage6EnforcementTests.cs
+++ b/tests/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer.Tests/NodeManagerStage6EnforcementTests.cs
@@ -229,6 +229,45 @@ public sealed class NodeManagerStage6EnforcementTests : IDisposable
     }
 
 
+    /// <summary>
+    ///     Event subscriptions are gated, and the gate resolves its source through the SDK's own
+    ///     <c>IsHandleInNamespace</c> rather than a cast.
+    /// </summary>
+    /// <remarks>
+    ///     <para>
+    ///         ⚠️ This exists because the first version of that gate read <c>sourceId as NodeState</c>.
+    ///         <c>sourceId</c> is the manager <b>handle</b>, so the cast compiled, always yielded null, and
+    ///         silently disabled the gate — the same <c>object</c>-typed trap as
+    ///         <c>ContinuationPoint.NodeToBrowse</c>. Nothing about the code looked wrong.
+    ///     </para>
+    ///     <para>
+    ///         The monitored item is deliberately <see langword="null"/>: a denial must be reached without
+    ///         the gate touching the item at all. That also makes the test a discriminator rather than a
+    ///         restatement — against the broken cast the gate falls through to the base implementation,
+    ///         which does dereference the item, so the test fails loudly instead of passing.
+    ///     </para>
+    /// </remarks>
+    [Fact]
+    public async Task Event_subscriptions_are_gated_on_the_notifier()
+    {
+        var (host, server) = await BootAsync();
+        try
+        {
+            var nm = server.NodeManager!;
+            nm.Authorizer = Authorizer(enabled: true, GrantOn(NodePermissions.Read));
+            var nodeId = Variable(nm, "Plant/Modbus/dev1/Speed");
+
+            var context = new OperationContext(
+                new RequestHeader(), secureChannelContext: null, RequestType.CreateMonitoredItems, Identity());
+
+            var result = nm.SubscribeToEvents(
+                context, nm.GetManagerHandle(nodeId), subscriptionId: 1, monitoredItem: null!, unsubscribe: false);
+
+            result.StatusCode.Code.ShouldBe(StatusCodes.BadUserAccessDenied);
+        }
+        finally { await host.DisposeAsync(); }
+    }
+
     // ───────────────────────────── helpers ─────────────────────────────
 
     private static NodeId Variable(OtOpcUaNodeManager nm, string rawPath)