([#122612](https://github.com/kubernetes/kubernetes/pull/122612), [@mtardy](https://github.com/mtardy))

### API Change

- The default delegating authorization options now allow unauthenticated access to healthz, readyz, and livez.  A system:masters user connecting to an authz delegator will not perform an authz check. ([#98325](https://github.com/kubernetes/kubernetes/pull/98325), [@deads2k](https://github.com/deads2k)) [SIG API Machinery, Auth, Cloud Provider and Scheduling]

making security functions more understandable for users.

RBAC [cluster role aggregation](https://kubernetes.io/docs/reference/access-authn-authz/rbac/#aggregated-clusterroles), introduced in 1.9, graduated to stable status with no changes in 1.11, and [client-go credential plugins](https://kubernetes.io/docs/reference/access-authn-authz/authentication/#client-go-credential-plugins)  graduated to beta status, while also adding support for obtaining TLS credentials from an external plugin....

- kube-scheduler

### External credential providers

- The following features are unconditionally...

**Note**: This only impacts the cluster if the ServiceAccount admission plugin is used (most cluster should have this on by default as recommended in https://kubernetes.io/docs/reference/access-authn-authz/admission-controllers/#serviceaccount), the `kubernetes.io/enforce-mountable-secrets` annotation is used by a service account (this annotation is not added by default), and Pods are using ephemeral containers.

**Affected Versions**:

- Kube-apiserver: Added Alpha features to allow API server authz to check the context of requests:
  - The `AuthorizeWithSelectors` feature gate enables including field and label selector information from requests in webhook authorization calls.

* Default values differ between the Kubelet's componentconfig (config file) API and the Kubelet's command line. Be sure to review the default values when migrating to using a config file. For example, the authz mode is set to "AlwaysAllow" if you rely on the command line, but defaults to the more secure "Webhook" mode if you load config from a file. ([#59666](https://github.com/kubernetes/kubernetes/pull/59666), [@mtaufen](https://github.com/mtaufen))

* delegated authn/z: optionally opt-out of mandatory authn/authz kubeconfig ([#67545](https://github.com/kubernetes/kubernetes/pull/67545), [@sttts](https://github.com/sttts))