Merge pull request #228178 from miwithro/patch-211

Update concepts-security.md

Author: JamesJBarnett

articles/aks/concepts-security.md

@@ -4,7 +4,7 @@ description: Learn about security in Azure Kubernetes Service (AKS), including m
 services: container-service
 author: miwithro
 ms.topic: conceptual
-ms.date: 01/20/2022
+ms.date: 02/22/2023
 ms.author: miwithro
 ---
 
@@ -60,6 +60,8 @@ Each evening, Linux nodes in AKS get security patches through their distro secur
 
 Nightly updates apply security updates to the OS on the node, but the node image used to create nodes for your cluster remains unchanged. If a new Linux node is added to your cluster, the original image is used to create the node. This new node will receive all the security and kernel updates available during the automatic check every night but will remain unpatched until all checks and restarts are complete. You can use node image upgrade to check for and update node images used by your cluster. For more details on node image upgrade, see [Azure Kubernetes Service (AKS) node image upgrade][node-image-upgrade].
 
+For AKS clusters on auto upgrade channel "node-image" will not pull security updates through unattended upgrade. They will  get security updates through the weekly node image upgrade.
+
 #### Windows Server nodes
 
 For Windows Server nodes, Windows Update doesn't automatically run and apply the latest updates. Schedule Windows Server node pool upgrades in your AKS cluster around the regular Windows Update release cycle and your own validation process. This upgrade process creates nodes that run the latest Windows Server image and patches, then removes the older nodes. For more information on this process, see [Upgrade a node pool in AKS][nodepool-upgrade].