A security issue was discovered in Kubernetes where users may have access to secure endpoints in the control plane network. Kubernetes clusters are only affected if an untrusted user can to modify Node objects and send requests proxying through them.

- kubeadm: prevent overriding of certain kubelet security configuration parameters if the user wished to modify them ([#81903](https://github.com/kubernetes/kubernetes/pull/81903), [@jfbai](https://github.com/jfbai))

A security issue was discovered in Kubernetes where users may have access to secure endpoints in the control plane network. Kubernetes clusters are only affected if an untrusted user can to modify Node objects and send requests proxying through them.

### Scheduling
* **Multiple schedulers**
  * Modify your PodSpecs that currently use the `scheduler.alpha.kubernetes.io/name` annotation on Pod, to instead use the `schedulerName` field in the PodSpec.
  * Modify any custom scheduler(s) you have written so that they read the `schedulerName` field on Pod instead of the `scheduler.alpha.kubernetes.io/name` annotation.

* The `NodeRestriction` admission plugin limits the `Node` and `Pod` objects a kubelet can modify. In order to be limited by this admission plugin, kubelets must use credentials in the `system:nodes` group, with a username in the form `system:node:<nodeName>`. Such kubelets will only be allowed to modify their own `Node` API object, and only modify `Pod` API objects that are bound to their node. ([#45929](https://github.com/kubernetes/kubernetes/pull/45929), [@liggit...

    * If you are running E2E tests which require SSH keys and you utilize environment variables to override their location, you may need to modify the environment variable set. On all providers the environment variable override can now be either an absolute path to the key or a relative path (relative to ~/.ssh). Specifically the changes are:

- Added `UserNamespacesPodSecurityStandards` feature gate to enable user namespace support for Pod Security Standards.
  Enabling this feature will modify all Pod Security Standard rules to allow setting: `spec[.*].securityContext.[runAsNonRoot,runAsUser]`.
  This feature gate should only be enabled if all nodes in the cluster support the user namespace feature and have it enabled.