</p>

<p>
Implementation restriction: A compiler may restrict ImportPaths to
non-empty strings using only characters belonging to
<a href="https://www.unicode.org/versions/Unicode6.3.0/">Unicode's</a>
L, M, N, P, and S general categories (the Graphic characters without
spaces) and may also exclude the characters
<code>!"#$%&amp;'()*,:;&lt;=&gt;?[\]^`{|}</code>
and the Unicode replacement character U+FFFD.
</p>

<p>

- 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))

- 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

  // Defaulted to nil.
  // +optional
  optional bool immutable = 4;

  // Data contains the configuration data.
  // Each key must consist of alphanumeric characters, '-', '_' or '.'.
  // Values with non-UTF-8 byte sequences must use the BinaryData field.
  // The keys stored in Data must not overlap with the keys in
  // the BinaryData field, this is enforced during validation process.

- 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...

### 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))

### 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))

### 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))

- kubeadm: fixed a bug in the underlying library for diff related to characters like '%' ([#73941](https://github.com/kubernetes/kubernetes/pull/73941), [@neolit123](https://github.com/neolit123))

- Added a alpha feature, behind the `RelaxedEnvironmentVariableValidation` feature gate.
  When that gate is enabled, Kubernetes allows almost all printable ASCII characters to be used in the names
  of environment variables for containers in Pods. ([#123385](https://github.com/kubernetes/kubernetes/pull/123385), [@HirazawaUi](https://github.com/HirazawaUi))