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

  - `io.k8s.apimachinery.pkg.apis.meta.v1.Status_v2` ([#110179](https://github.com/kubernetes/kubernetes/pull/110179), [@Jefftree](https://github.com/Jefftree))
- Panics while calling validating admission webhook are caught and honor the fail open or fail closed setting. ([#108746](https://github.com/kubernetes/kubernetes/pull/108746), [@deads2k](https://github.com/deads2k)) [SIG API Machinery]

- kube-scheduler

- Apiservers based on k8s.io/apiserver with delegated authn based on cluster authentication will automatically update to new authentication information when the authoritative configmap is updated. ([#85004](https://github.com/kubernetes/kubernetes/pull/85004), [@deads2k](https://github.com/deads2k))

and on 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...

### External credential providers

- The following features are unconditionally...

* Ensure the KUBE-MARK-DROP chain in kube-proxy mode=ipvs....

**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.

**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.