- Kubeadm: modify '--config' flag from required to optional for 'kubeadm kubeconfig user' command ([#116074](https://github.com/kubernetes/kubernetes/pull/116074), [@SataQiu](https://github.com/SataQiu)) [SIG Cluster Lifecycle]

* 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...

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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.

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:  in the new output API "output.kubeadm.k8s.io/v1alpha3" modify the UpgradePlan structure that is used when calling "kubeadm upgrade plan ... -o yaml|json", to include a list of multiple available upgrades. ([#123461](https://github.com/kubernetes/kubernetes/pull/123461), [@carlory](https://github.com/carlory))...

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions: