- The API server and client-go libraries have been fixed to support additional non-alpha-numeric characters in UserInfo "extra" data keys. Both should be updated in order to properly support extra data containing "/" characters or other characters disallowed in HTTP headers. ([#65799](https://github.com/kubernetes/kubernetes/pull/65799), [@dekkagaijin](https://github.com/dekkagaijin)) Courtesy of SIG Auth

### Action Required

* action required: the API server and client-go libraries have been fixed to support additional non-alpha-numeric characters in UserInfo "extra" data keys. Both should be updated in order to properly support extra data containing "/" characters or other characters disallowed in HTTP headers. ([#65799](https://github.com/kubernetes/kubernetes/pull/65799), [@dekkagaijin](https://github.com/dekkagaijin))

- Fixed EndpointSlice port name validation to match Endpoint port name validation (allowing port names longer than 15 characters) ([#84481](https://github.com/kubernetes/kubernetes/pull/84481), [@robscott](https://github.com/robscott))

### Action Required

* action required: the API server and client-go libraries have been fixed to support additional non-alpha-numeric characters in UserInfo "extra" data keys. Both should be updated in order to properly support extra data containing "/" characters or other characters disallowed in HTTP headers. ([#65799](https://github.com/kubernetes/kubernetes/pull/65799), [@dekkagaijin](https://github.com/dekkagaijin))

### Failing Test

- Escape the special characters like `[`, `]` and ` ` that exist in vsphere windows path ([#98830](https://github.com/kubernetes/kubernetes/pull/98830), [@liyanhui1228](https://github.com/liyanhui1228)) [SIG Storage and Windows]

- Fixed CSI `PersistentVolumes` to allow Secrets names longer than 63 characters. ([#114776](https://github.com/kubernetes/kubernetes/pull/114776), [@jsafrane](https://github.com/jsafrane))

### Action Required

* action required: the API server and client-go libraries have been fixed to support additional non-alpha-numeric characters in UserInfo "extra" data keys. Both should be updated in order to properly support extra data containing "/" characters or other characters disallowed in HTTP headers. ([#65799](https://github.com/kubernetes/kubernetes/pull/65799), [@dekkagaijin](https://github.com/dekkagaijin))

## Changelog since v1.18.16

## Changes by Kind

### Failing Test

- Fix handing special characters in the volume path on Windows ([#99138](https://github.com/kubernetes/kubernetes/pull/99138), [@yujuhong](https://github.com/yujuhong)) [SIG Storage]

### Bug or Regression

- Kubeadm: external etcd endpoints passed in the `ClusterConfiguration` that have Unicode characters are no longer IDNA encoded (converted to Punycode). They are now just URL encoded as per Go's implementation of RFC-3986, have duplicate "/" removed from the URL paths, and passed like that directly to the `kube-apiserver` `--etcd-servers` flag. If you have etcd endpoints that have Unicode characters, it is advisable to encode them in advance with tooling that is fully IDNA compliant. If you don't...

- Limit vSphere volume name to 63 characters long. ([#100404](https://github.com/kubernetes/kubernetes/pull/100404), [@gnufied](https://github.com/gnufied))