}
      }
    ```

### Handling authentication ([.kt][AuthenticateKotlin], [.java][AuthenticateJava])

OkHttp can automatically retry unauthenticated requests. When a response is `401 Not Authorized`, an `Authenticator` is asked to supply credentials. Implementations should build a new request that includes the missing credentials. If no credentials are available, return null to skip the retry.

        * Nodes must use client credentials that place them in the `system:nodes` group with a username of `system:node:<nodeName>` in order to be authorized by the node authorizer (the credentials obtained by the kubelet...

   ([#123611](https://github.com/kubernetes/kubernetes/pull/123611), [@ritazh](https://github.com/ritazh))

- In the course of admitting a single request, the ValidatingAdmissionPolicy plugin will perform no more than one authorization check per unique authorizer expression. All evaluations of identical authorizer expressions will produce the same decision. ([#116443](https://github.com/kubernetes/kubernetes/pull/116443), [@benluddy](https://github.com/benluddy)) [SIG API Machinery and Testing]

		Description:    "The service is unavailable. Please retry.",
		HTTPStatusCode: http.StatusServiceUnavailable,
	},
	ErrUnauthorizedAccess: {
		Code:           "UnauthorizedAccess",
		Description:    "You are not authorized to perform this operation",
		HTTPStatusCode: http.StatusUnauthorized,
	},
	ErrExpressionTooLong: {
		Code:           "ExpressionTooLong",

- Improves performance of the node authorizer ([#87696](https://github.com/kubernetes/kubernetes/pull/87696), [@liggitt](https://github.com/liggitt)) [SIG Auth]

* Add support for the webhook authorizer to make a Deny decision that short-circuits the union authorizer and immediately returns Deny.  ([#53273](https://github.com/kubernetes/kubernetes/pull/53273), [@mikedanese](https://github.com/mikedanese))

- Added authorization check support to the CEL expressions of ValidatingAdmissionPolicy via a `authorizer`

object by patching themselves with an OwnerReference to a cluster-scoped resource. If the OwnerReference resource does not exist or is subsequently deleted, the given node object will be deleted via garbage collection. By default, node users are authorized for create and patch requests but not delete requests against their node object. Since the NodeRestriction admission controller does not prevent patching OwnerReferences, a compromised node could leverage this vulnerability to delete and then recreate...

* `list`/`watch` API requests with a `fieldSelector` that specifies `metadata.name` can now be authorized as requests for an individual named resource ([#63469](https://github.com/kubernetes/kubernetes/pull/63469), [@wojtek-t](https://github.com/wojtek-t))