- Kube-apiserver can now specify `--authentication-token-webhook-version=v1` or `--authorization-webhook-version=v1` to use `v1` TokenReview and SubjectAccessReview API objects when communicating with authentication and authorization webhooks. ([#84768](https://github.com/kubernetes/kubernetes/pull/84768), [@liggitt](https://github.com/liggitt))

- JWT authenticator config set via the --authentication-config flag is now dynamically reloaded as the file changes on disk. ([#123525](https://github.com/kubernetes/kubernetes/pull/123525), [@enj](https://github.com/enj)) [SIG API Machinery, Auth and Testing]

### API Change

- '`kube-apiserver`: adds `--authentication-config` flag for reading `AuthenticationConfiguration`
  files. `--authentication-config` flag is mutually exclusive with the existing `--oidc-*`
  flags.' ([#119142](https://github.com/kubernetes/kubernetes/pull/119142), [@aramase](https://github.com/aramase))

  // chapAuthDiscovery defines whether support iSCSI Discovery CHAP authentication
  // +optional
  optional bool chapAuthDiscovery = 8;

  // chapAuthSession defines whether support iSCSI Session CHAP authentication
  // +optional
  optional bool chapAuthSession = 11;

  // secretRef is the CHAP Secret for iSCSI target and initiator authentication
  // +optional
  optional SecretReference secretRef = 10;

- Fix bug to prevent allocation of existing floating IP.
- Fix Cinder authentication bug when OS_DOMAIN_NAME not specified.
- Fix Keystone authentication errors by skipping synchronization for unscoped tokens.
- Fix authentication error for client-auth-plugin
- Fix dependency references from in-tree-provider to point to external provider.
- Add shutdown instance by Provider ID.

* kube-apiserver: OIDC authentication now supports requiring specific claims with `--oidc-required-claim=<claim>=<value>` Previously, there was no mechanism for a user to specify claims in the OIDC authentication process that were requid to be present in the ID Token with an expected value. This version now makes it possible to require claims support for the OIDC authentication. It allows users to pass in a `--oidc-required-claims` flag, and `key=value`...

  - `--address`
  The insecure port flags `--port` may only be set to 0 now.
  
  In addtion, please be careful that:
  - controller-manager MUST start with `--authorization-kubeconfig` and `--authentication-kubeconfig` correctly set to get authentication/authorization working.
  - liveness/readiness probes to controller-manager MUST use HTTPS now, and the default port has been changed to 10257.

    - [kubeadm](#kubeadm-1)
    - [Other Deprecations](#other-deprecations)
  - [Changes to API Resources](#changes-to-api-resources)
    - [ABAC](#abac)
    - [Admission Control](#admission-control)
    - [Authentication](#authentication)
    - [Authorization](#authorization)
    - [Autoscaling](#autoscaling-1)
    - [Certificates](#certificates)
    - [ConfigMap](#configmap)
    - [CronJob](#cronjob)
    - [DaemonSet](#daemonset-1)

- `system:kube-controller-manager` and `system:kube-scheduler` users are now permitted to perform delegated authentication/authorization checks by default RBAC policy ([#72491](https://github.com/kubernetes/kubernetes/pull/72491), [@liggitt](https://github.com/liggitt))

* API server authentication now caches successful bearer token authentication results for a few seconds. ([#50258](https://github.com/kubernetes/kubernetes/pull/50258), [@liggitt](https://github.com/liggitt))