* v1.Pod now has a field to configure whether a single process namespace should be shared between all containers in a pod. This feature is in alpha preview. ([#58716](https://github.com/kubernetes/kubernetes/pull/58716), [@verb](https://github.com/verb))

*   Azure NSG rules can be consolidated to reduce the likelihood of hitting Azure resource limits (available only in regions where the Augmented Security Groups preview is available).  ([#55740](https://github.com/kubernetes/kubernetes/pull/55740), [@itowlson](https://github.com/itowlson))

- Renames the timeout field for the DelegatingAuthenticationOptions to TokenRequestTimeout and set the timeout only for the token review client. Previously the timeout was also applied to watches making them reconnecting every 10 seconds. ([#101102](https://github.com/kubernetes/kubernetes/pull/101102), [@p0lyn0mial](https://github.com/p0lyn0mial)) [SIG API Machinery, Auth and Cloud...

3. Ensure you have added or ran the appropriate tests for your PR: https://git.k8s.io/community/contributors/devel/sig-testing/testing.md
4. If you want *faster* PR reviews, read how: https://git.k8s.io/community/contributors/guide/pull-requests.md#best-practices-for-faster-reviews
5. If the PR is unfinished, see how to mark it: https://git.k8s.io/community/contributors/guide/pull-requests.md#marking-unfinished-pull-requests
-->

* Added golint check for pkg/kubelet. ([#47316](https://github.com/kubernetes/kubernetes/pull/47316), [@k82cn](https://github.com/k82cn))
* azure: acr: support MSI with preview ACR with AAD auth ([#48981](https://github.com/kubernetes/kubernetes/pull/48981), [@colemickens](https://github.com/colemickens))

  * Plugins

      * Introduces the ability to extend kubectl by adding third-party plugins. Developer preview, please refer to the documentation for instructions about how to use it. ([#37499](https://github.com/kubernetes/kubernetes/pull/37499), [@fabianofranz](https://github.com/fabianofranz))

- **Security**
  - Increased pod-level security granularity (eg: Container Image Policies, AppArmor and `sysctl` support)
  - Increased cluster-level security granularity (eg: Access Review API)

## Features

    - `kubectl create clusterrolebinding anonymous-discovery --clusterrole=system:discovery --group=system:unauthenticated`
    - `kubectl create clusterrolebinding anonymous-access-review --clusterrole=system:basic-user --group=system:unauthenticated`

- Added feature support to Windows for configuring session affinity of Kubernetes services.
  required: [Windows Server vNext Insider Preview Build 19551](https://blogs.windows.com/windowsexperience/2020/01/28/announcing-windows-server-vnext-insider-preview-build-19551/) (or higher) ([#91701](https://github.com/kubernetes/kubernetes/pull/91701), [@elweb9858](https://github.com/elweb9858)) [SIG Network and Windows]

**How can I mitigate this prior to installing 1.5.5?**

1. Export existing PodSecurityPolicy objects:
  * `kubectl get podsecuritypolicies -o yaml > psp.yaml`
2. Review and delete any PodSecurityPolicy objects you do not want all pod-creating users to be able to use (NOTE: Privileged users that were making use of those policies will also lose access to those policies). For example: