- Adds the ability to pass --strict-transport-security-directives to the kube-apiserver to set the HSTS header appropriately.  Be sure you understand the consequences to browsers before setting this field. ([#96502](https://github.com/kubernetes/kubernetes/pull/96502), [@249043822](https://github.com/249043822)) [SIG Auth]

- Kube-apiserver: regular expressions specified with the `--cors-allowed-origins` option are now validated to match the entire `hostname` inside the `Origin` header of the request and 
  must contain '^' or the '//' prefix to anchor to the start, and '$' or the port separator ':' to anchor to 

- Kube-proxy service health returns http header `X-Load-Balancing-Endpoint-Weight` with number of local endpoints. The same information is still available in response body JSON `payload.LocalEndpoints`. ([#118999](https://github.com/kubernetes/kubernetes/pull/118999), [@cezarygerard](https://g...

* add fieldSelector podIP ([#50091](https://github.com/kubernetes/kubernetes/pull/50091), [@dixudx](https://github.com/dixudx))
* Return Audit-Id http response header for trouble shooting ([#49377](https://github.com/kubernetes/kubernetes/pull/49377), [@CaoShuFeng](https://github.com/CaoShuFeng))

- `--log-flush-frequency` had no effect in several commands or was missing. Help and warning texts were not always using the right format for a command (`add_dir_header` instead of `add-dir-header`). Fixing this included cleaning up flag handling in component-base/logs: that package no longer adds flags to the global flag sets. Commands which want the klog and `--log-flush-frequency` flags must explicitly call `logs.AddFlags`;...

- Added a path `/header?key=` to `agnhost netexec` allowing one to view what the header value is of the incoming request.

  Ex:
  ```
  $ curl -H "X-Forwarded-For: something" 172.17.0.2:8080/header?key=X-Forwarded-For
  something
  ```

- Kube API server accepts `Impersonate-Uid` header to impersonate a user with a specific UID, in the same way that you can currently use `Impersonate-User`, `Impersonate-Group` and `Impersonate-Extra`. ([#99961](https://github.com/kubernetes/kubernetes/pull/99961), [@margocrawf](https://github.com/margocrawf))...