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 and the `kubernetes.io/enforce-mountable-secrets` annotation are used together with ephemeral containers.

**Note**:...

- E2e tests wait for kube-root-ca.crt to be populated in namespaces for use with projected service account tokens, reducing delays starting those test pods and errors in the logs. ([#108860](https://github.com/kubernetes/kubernetes/pull/108860), [@eddiezane](https://github.com/eddiezane)) [SIG Testing]

- Get-kube.sh uses the gcloud's current local GCP service account for auth when the provider is GCE or GKE instead of the metadata server default ([#88383](https://github.com/kubernetes/kubernetes/pull/88383), [@BenTheElder](https://github.com/BenTheElder)) [SIG Cluster Lifecycle]

- Authentication token cache size is increased (from 4k to 32k) to support clusters with many nodes or many namespaces with active service accounts. ([#83643](https://github.com/kubernetes/kubernetes/pull/83643), [@lavalamp](https://github.com/lavalamp))

resource belongs to. ([#43338](https://github.com/kubernetes/kubernetes/pull/43338), [@fabianofranz](https://github.com/fabianofranz))

* `--service-account-lookup` now defaults to true, requiring the Secret API object containing the token to exist in order for a service account token to be valid. This enables service account tokens to be revoked by deleting the Secret object containing the token. ([#44071](https://github.com/kubernetes/kubernetes/pull/44071), [@liggitt](https://github.com/liggitt))...

* The `kube-cloud-controller-manager` flag `--service-account-private-key-file` was non-functional and is now deprecated. ([#50289](https://github.com/kubernetes/kubernetes/pull/50289), [@liggitt](https://github.com/liggitt))
    * The `kube-cloud-controller-manager` flag `--use-service-account-credentials` is now honored consistently, regardless of whether `--service-account-private-key-file` was specified.

### SIG Auth

- TokenRequest and TokenRequestProjection are now beta features. To enable these feature, the API server needs to be started with the `--service-account-issuer`, `--service-account-signing-key-file`, and `--service-account-api-audiences` flags.
([#67349](https://github.com/kubernetes/kubernetes/pull/67349), [@mikedanese](https://github.com/mikedanese))

* The `kube-cloud-controller-manager` flag `--service-account-private-key-file` was non-functional and is now deprecated. ([#50289](https://github.com/kubernetes/kubernetes/pull/50289), [@liggitt](https://github.com/liggitt))
    * The `kube-cloud-controller-manager` flag `--use-service-account-credentials` is now honored consistently, regardless of whether `--service-account-private-key-file` was specified.

### CSI Service Account Token

  // Pods are only limited to this list if this service account has a "kubernetes.io/enforce-mountable-secrets" annotation set to "true".
  // This field should not be used to find auto-generated service account token secrets for use outside of pods.
  // Instead, tokens can be requested directly using the TokenRequest API, or service account token secrets can be manually created.