- `Kubelet` no longer creates certain legacy iptables rules by default.
  It is possible that this will cause problems with some third-party components
  that improperly depended on those rules. If this affects you, you can run

- The kube-proxy `sync_proxy_rules_iptables_total` metric has now reverted back
  to its pre-1.27 behavior of tracking the total number of iptables rules that
  kube-proxy is responsible for, rather than only counting the number of rules
  that it re-synced on the last sync. The new `sync_proxy_rules_iptables_last`

* Fix issue where masquerade rules are flushed in GCE k8s clusters. ([#56729](https://github.com/kubernetes/kubernetes/pull/56729), [@dnardo](https://github.com/dnardo))
* kubelet: Fix bug where `runAsUser: MustRunAsNonRoot` strategy didn't reject a pod with a non-numeric `USER`. ([#56708](https://github.com/kubernetes/kubernetes/pull/56708), [@php-coder](https://github.com/php-coder))

- kubeadm: Added better handling of errors during unmount when calling `kubeadm reset`. When failing to unmount directories under `/var/run/kubelet`, kubeadm will now throw an error instead of showing a warning and continuing to clean up said directory. In such situations, it is better for you to inspect the problem and resolve it manually. Then, you can call `kubeadm reset` again to complete the cleanup.

## Changelog since v1.26.8

## Changes by Kind

### API Change

- Fixed a bug where CEL expressions in CRD validation rules would incorrectly compute a high estimated cost for functions that return strings, lists or maps.

- Fixes a race condition in the iptables mode of kube-proxy in 1.27 and later
  that could result in some updates getting lost (e.g., when a service gets a
  new endpoint, the rules for the new endpoint might not be added until
  much later). ([#122756](https://github.com/kubernetes/kubernetes/pull/122756), [@hakman](https://github.com/hakman)) [SIG Network]