- Kubeadm: during the validation of existing kubeconfig files on disk, handle cases where the "ca.crt" is a bundle and has intermediate certificates. Find a common trust anchor between the "ca.crt" bundle and the CA in the existing kubeconfig on disk instead of treating "ca.crt" as a file containing a single CA. ([#123102](https://github.com/kubernetes/kubernetes/pull/123102), [@astundzia](h...

- Kubeadm`: modified `--config` flag from required to optional for `kubeadm kubeconfig user` command ([#116074](https://github.com/kubernetes/kubernetes/pull/116074), [@SataQiu](https://github.com/SataQiu))

### Other (Cleanup or Flake)

  much later). ([#122204](https://github.com/kubernetes/kubernetes/pull/122204), [@danwinship](https://github.com/danwinship))
- Fixed a regression in "kubeadm init" where a user-specified --kubeconfig file was being ignored. ([#122735](https://github.com/kubernetes/kubernetes/pull/122735), [@avorima](https://github.com/avorima))
- Fixed a regression in kubectl version `1.29.0` where the `--attach` flag was not honored.

- Kubeadm: Added support for additional authentication strategies in `kubeadm join` with discovery/kubeconfig file: client-go authentication plugins (`exec`), `tokenFile`, and `authProvider.` ([#110553](https://github.com/kubernetes/kubernetes/pull/110553), [@tallaxes](https://github.com/tallaxes))