Connect authenticator can now verify ID Tokens signed with JOSE algorithms other than RS256 through the --oidc-signing-algs flag. ([#58544](https://github.com/kubernetes/kubernetes/pull/58544), [@ericchiang](https://github.com/ericchiang))

* Requests with invalid credentials no longer match audit policy rules where users or groups are set, correcting a problem where authorized requests were getting through. ([#59398](https://github.com/kubernetes/kubernetes/pull/59398), [@CaoShuFeng](https...

* Horizontal pod autoscaler uses REST clients through the kube-aggregator instead of the legacy client through the API server proxy. ([#53205](https://github.com/kubernetes/kubernetes/pull/53205), [@kawych](https://github.com/kawych))

  - [Changelog since v1.26.0](#changelog-since-v1260)
  - [Known Issues](#known-issues)
    - [The PreEnqueue extension point doesn't work for Pods going to activeQ through backoffQ](#the-preenqueue-extension-point-doesnt-work-for-pods-going-to-activeq-through-backoffq)
  - [Urgent Upgrade Notes](#urgent-upgrade-notes)
    - [(No, really, you MUST read this before you upgrade)](#no-really-you-must-read-this-before-you-upgrade)

 
## Changes by Kind

### Deprecation

- Aborting the drain command in a list of nodes will be deprecated. The new behavior will make the drain command go through all nodes even if one or more nodes failed during the drain. For now, users can try such experience by enabling --ignore-errors flag. ([#98203](https://github.com/kubernetes/kubernetes/pull/98203), [@yuzhiquan](https://github.com/yuzhiquan))

Node object.

**Note**: This only impacts validating admission plugins that rely on old
values in certain fields, and does not impact calls from kubelets that go
through the built-in NodeRestriction admission plugin.

**Affected Versions**:
  - kube-apiserver v1.20.0 - v1.20.5
  - kube-apiserver v1.19.0 - v1.19.9
  - kube-apiserver <= v1.18.17

**Fixed Versions**:

* [beta] Advanced auditing has been promoted from alpha to beta. The webhook and logging policy formats have changed since alpha, and may require modification.

* [beta] Kubelet certificate rotation through the certificates API has been promoted from alpha to beta. RBAC cluster roles for the certificates controller have been added for common uses of the certificates API, such as the kubelet's.

- Kubelet metrics gathered through metrics-server or prometheus should no longer timeout for Windows nodes running more than 3 pods. ([#87730](https://github.com/kubernetes/kubernetes/pull/87730), [@marosset](https://github.com/marosset)) [SIG Node, Testing and Windows]

- Added additional validation for endpoint IP configuration while iterating through queried endpoint list. ([#116749](https://github.com/kubernetes/kubernetes/pull/116749), [@princepereira](https://github.com/princepereira))

- In clusters where the DryRun feature is enabled, dry-run requests will go through the normal admission chain. Because of this, ImagePolicyWebhook authors should especially make sure that their webhooks do not rely on side effects. ([#66391](https://github.com/kubernetes/kubernetes/pull/66391), [@jennybuckley](https://github.com/jennybuckley))...

* Resolves a bug that prevented sending a multi-version custom resource to an admission webhook. ([#79495](https://github.com/kubernetes/kubernetes/pull/79495), [@liggitt](https://github.com/liggitt))
* Pass-through volume MountOptions to global mount (NodeStageVolume) on the node for CSI ([#80191](https://github.com/kubernetes/kubernetes/pull/80191), [@davidz627](https://github.com/davidz627))