* Allows extension API server to dynamically discover the requestheader CA certificate when the core API server doesn't use certificate based authentication for it's clients ([#66394](https://github.com/kubernetes/kubernetes/pull/66394), [@rtripat](https://github.com/rtripat))

- github.com/google/s2a-go: [v0.1.7](https://github.com/google/s2a-go/tree/v0.1.7)
- github.com/googleapis/enterprise-certificate-proxy: [v0.2.3](https://github.com/googleapis/enterprise-certificate-proxy/tree/v0.2.3)
- google.golang.org/genproto/googleapis/bytestream: e85fd2c
- google.golang.org/grpc/cmd/protoc-gen-go-grpc: v1.1.0
- gopkg.in/gcfg.v1: v1.2.3

* Fixes request header authenticator by presenting the request header client CA so that the front proxy will authenticate using its client certificate. ([#40301](https://github.com/kubernetes/kubernetes/pull/40301), [@deads2k](https://github.com/deads2k))

- The `CertificateSigningRequest.certificates.k8s.io` API supports an optional expirationSeconds field to allow the client to request a particular duration for the issued certificate.  The default signer implementations provided by the Kubernetes controller manager will honor this field as long as it does not exceed the --cluster-signing-duration flag. ([#99494](https://github.com/kubernetes/kubernetes/pull/99494), [@enj](h...

- Fixes an issue where the vsphere cloud provider will not trust a certificate if:
  - The issuer of the certificate is unknown (x509.UnknownAuthorityError)
  - The requested name does not match the set of authorized names (x509.HostnameError)

- X.509 client certificate authentication to the kube-apiserver now produces credential IDs (derived from the certificate's signature) , for use in audit logging. ([#125634](https://github.com/kubernetes/kubernetes/pull/125634), [@ahmedtd](https://github.com/ahmedtd)) [SIG...

# Search Engine

# The type of search engine backend (e.g., default, opensearch).
search_engine.type=default
# The URL of the search engine HTTP endpoint.
search_engine.http.url=http://localhost:9201
# Path to SSL certificate authorities for secure HTTP connections.
search_engine.http.ssl.certificate_authorities=
# Username for authenticating to the search engine.
search_engine.username=
# Password for authenticating to the search engine.

- Kubeadm: removed the restriction that the `ca.crt` can only contain one certificate. If there is more than one certificate in the `ca.crt` file, kubeadm will pick the first one by default. ([#107327](https://github.com/kubernetes/kubernetes/pull/107327), [@SataQiu](https://github.com/SataQiu))

- Be able to create a Pod with Generic Ephemeral Volumes as raw block devices. ([#105682](https://github.com/kubernetes/kubernetes/pull/105682), [@pohly](https://github.com/pohly))
- CA, certificate and key bundles for the `generic-apiserver` based servers will be reloaded immediately after the files are changed. ([#104102](https://github.com/kubernetes/kubernetes/pull/104102), [@tnqn](https://github.com/tnqn))

- Resolves an issue using `kubectl certificate approve/deny` against a server serving the v1 CSR API ([#91691](https://github.com/kubernetes/kubernetes/pull/91691), [@liggitt](https://github.com/liggitt)) [SIG Auth and CLI]

### Other (Cleanup or Flake)