- Relaxed API validation to allow pod node selector to be mutable for gated pods (additions only, no deletions or mutations). ([#116161](https://github.com/kubernetes/kubernetes/pull/116161), [@danielvegamyhre](https://github.com/danielvegamyhre))

* kubeadm: fixed incorrect controller manager pod mutations during selfhosting pivoting ([#72518](https://github.com/kubernetes/kubernetes/pull/72518), [@bart0sh](https://github.com/bart0sh))

* The dynamic Kubelet config feature will now update the config in the event of a ConfigMap mutation, which reduces the chance for silent config skew. Only name, namespace, and kubeletConfigKey may now be set in `Node.Spec.ConfigSource.ConfigMap`. The least disruptive pattern for config management is still to create a new ConfigMap and incrementally...

- Introduced `v1alpha1` API for mutating admission policies, enabling extensible #     admission control via CEL expressions (KEP  3962: Mutating Admission Policies). #     To use, enable the `MutatingAdmissionPolicy` feature gate and the `admissionregistration.k8s.io/v1alpha1` #     API via `--runtime-config`. ([#127134](https://github....

### **API Machinery**

#### **Admission Control**

*   Admission webhooks are now in beta, and include the following:
    *   Mutation support for admission webhooks. ([#54892](https://github.com/kubernetes/kubernetes/pull/54892),[ @caesarxuchao](https://github.com/caesarxuchao))

- Kubeadm: retry `kubeadm-config` ConfigMap creation or mutation if the apiserver is not responding. This will improve resiliency when joining new control plane nodes. ([#85763](https://github.com/kubernetes/kubernetes/pull/85763), [@ereslibre](https://github.com/ereslibre)) [SIG Cluster Lifecycle]

- kube-apiserver: Authentication configuration for mutating and validating admission webhooks referenced from an `--admission-control-config-file` can now be specified with `apiVersion: apiserver.config.k8s.io/v1, kind: WebhookAdmissionConfiguration`. ([#85138](https://github.com/kubernetes/kubernetes/pull/85138),...

- kube-apiserver: setting a `dryRun` query parameter on a CONNECT request will now cause the request to be rejected, consistent with behavior of other mutating API requests. Examples of CONNECT APIs are the `nodes/proxy`, `services/proxy`, `pods/proxy`, `pods/exec`, and `pods/attach` subresources. Note that this prevents sending a `dryRun` parameter to backends via `{nodes,services,pods}/proxy` subresources....

* Bump GCE metadata proxy to v0.1.9 to pick up security fixes. ([#58221](https://github.com/kubernetes/kubernetes/pull/58221), [@ihmccreery](https://github.com/ihmccreery))
* kubeadm now supports CIDR notations in NO_PROXY environment variable ([#53895](https://github.com/kubernetes/kubernetes/pull/53895), [@kad](https://github.com/kad))

 in your manifest. An object with a spec.selector value that does not match the labels in
 its spec.template is invalid.

 - Selector mutation is disabled for all kinds in the
 app/v1beta2 group version, because the controllers in the workloads API do not handle
 selector mutation in
 a consistent way. This restriction may be lifted in the future, but
 it is likely that that selectors will remain immutable after the move to v1.