enforce mountable secrets policy imposed by the ServiceAccount admission plugin

A security issue was discovered in Kubernetes where users may be able to launch containers that bypass the mountable secrets policy enforced by the ServiceAccount admission plugin when using ephemeral containers. The policy ensures pods running with a service account may only reference secrets specified in the service account's secrets field. Kubernetes clusters are only affected if the ServiceAccount admission plugin...

  - `--port`
  - `--address`
  The insecure port flags `--port` may only be set to 0 now.
- Kube-scheduler: the `--port` and `--address` flags have no effect and would be removed in v1.24.
  The insecure port flags `--port` may only be set to 0 now.

## Urgent Upgrade Notes 

### (No, really, you MUST read this before you upgrade)

    - [Workloads that saturate nodes with pods may see pods that fail due to node admission](#workloads-that-saturate-nodes-with-pods-may-see-pods-that-fail-due-to-node-admission)
    - [Etcd v3.5.[0-2] data corruption](#etcd-v350-2-data-corruption)
  - [Urgent Upgrade Notes](#urgent-upgrade-notes)

mitigation for http/2 DOS vulnerabilities for CVE-2023-44487 and CVE-2023-39325 for the API server when the client is unauthenticated. The mitigation may be enabled by setting the `UnauthenticatedHTTP2DOSMitigation` feature gate to `true` (it is disabled by default). An API server fronted by an L7 load balancer that already mitigates these http/2 attacks may choose not to enable the kube-apiserver mitigation to avoid disrupting load balancer → kube-apiserver connections if http/2 requests from multiple...

  - `spec.signerName` is now required, and requests for `kubernetes.io/legacy-unknown` are not allowed to be created via the `certificates.k8s.io/v1` API
  - `spec.usages` is now required, may not contain duplicate values, and must only contain known usages
  - `status.conditions` may not contain duplicate types
  - `status.conditions[*].status` is now required

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          do not modify the License. You may add Your own attribution
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          do not modify the License. You may add Your own attribution
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