* The kube-apiserver [basic audit log](https://kubernetes.io/docs/admin/audit/) can be enabled in GCE by exporting the environment variable `ENABLE_APISERVER_BASIC_AUDIT=true` before running `cluster/kube-up.sh`. This will log to `/var/log/kube-apiserver-audit.log` and use the same `logrotate` settings as `/var/log/kube-apiserver.log`. ([#41211](https://github.com/kubernetes/kubernetes/pull/41211), [@enisoc](ht...

* [Experiment Only] When using kube-up.sh on GCE, user could set env `KUBE_PROXY_DAEMONSET=true` to run kube-proxy as a DaemonSet. kube-proxy is run as static pods by default. ([#50705](https://github.com/kubernetes/kubernetes/pull/50705), [@MrHohn](https://github.com/MrHohn))

  - ip-mask-agent addon starts to use the label `node.kubernetes.io/masq-agent-ds-ready` instead of `beta.kubernetes.io/masq-agent-ds-ready` as its node selector.
  - kube-proxy addon starts to use the label `node.kubernetes.io/kube-proxy-ds-ready` instead of `beta.kubernetes.io/kube-proxy-ds-ready` as its node selector.

Before upgrading to Kubernetes 1.13, you must keep the following in mind:

- kube-apiserver

- kubeadm: Control plane images (etcd, kube-apiserver, kube-proxy, etc.) no longer use arch suffixes. Arch suffixes are kept for kube-dns only. ([#66960](https://github.com/kubernetes/kubernetes/pull/66960),...

through the built-in NodeRestriction admission plugin.

**Affected Versions**:
  - kube-apiserver v1.20.0 - v1.20.5
  - kube-apiserver v1.19.0 - v1.19.9
  - kube-apiserver <= v1.18.17

**Fixed Versions**:
  - kube-apiserver v1.21.0
  - kube-apiserver v1.20.6
  - kube-apiserver v1.19.10
  - kube-apiserver v1.18.18

This vulnerability was reported by Rogerio Bastos & Ari Lima from RedHat

- kube-proxy no longer automatically cleans up network rules created by running kube-proxy in other modes. If you are switching the kube-proxy mode (EG: iptables to IPVS), you will need to run `kube-proxy --cleanup`, or restart the worker node (recommended) before restarting kube-proxy. If you are not switching kube-proxy between different modes, this change should not require any action. ([#76109](https://...

      - [Instrumentation](#instrumentation-1)
      - [Internal storage layer](#internal-storage-layer)
      - [Kubernetes Dashboard](#kubernetes-dashboard)
      - [kube-dns](#kube-dns)
      - [kube-proxy](#kube-proxy-1)
      - [kube-scheduler](#kube-scheduler)
      - [Storage](#storage-2)
      - [Networking](#networking-1)
      - [Node controller](#node-controller)
      - [Node Components](#node-components-1)

* AWS: Change default networking for kube-up to kubenet ([#32239](https://github.com/kubernetes/kubernetes/pull/32239), [@zmerlynn](https://github.com/zmerlynn))
* Make sure finalizers prevent deletion on storage that supports graceful deletion ([#32351](https://github.com/kubernetes/kubernetes/pull/32351), [@caesarxuchao](https://github.com/caesarxuchao))

      - [Multi-platform](#multi-platform)
      - [Cloud Providers](#cloud-providers)
    - [Network](#network)
      - [network-policy](#network-policy)
      - [kube-proxy ipvs mode](#kube-proxy-ipvs-mode)
    - [API Machinery](#api-machinery)
      - [kube-apiserver](#kube-apiserver)
      - [Dynamic Admission Control](#dynamic-admission-control)
      - [Custom Resource Definitions (CRDs)](#custom-resource-definitions-crds)