- `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

- Kube-proxy iptables: new metric sync_proxy_rules_iptables_total that exposes the number of rules programmed per table in each iteration ([#99653](https://github.com/kubernetes/kubernetes/pull/99653), [@aojea](https://github.com/aojea)) [SIG Instrumentation and Network]

- 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))

- In "large" clusters, kube-proxy in iptables mode will now sometimes
  leave unused rules in iptables for a while (up to `--iptables-sync-period`)
  before deleting them. This improves performance by not requiring it to
  check for stale rules on every sync. (In smaller clusters, it will still
  remove unused rules immediately once they are no longer used.)

- CEL regex patterns in x-kubernetes-valiation rules are compiled when CRDs are created/updated if the pattern is provided as a string constant in the expression. Any regex compile errors are reported as a CRD create/update validation error. ([#108617](https://github.com/kubernetes/kubernetes/pull/108617), [@jpbetz](https://github.com/jpbetz))

ig-1.22", while the new format does not - "kube-system/kubelet-config". A similar formatting change is done for the related RBAC rules. The old format is now DEPRECATED and will be removed after the feature graduates to GA. When writing the ConfigMap kubeadm (init, upgrade apply) will respect the value of UnversionedKubeletConfigMap, while when reading it (join, reset, upgrade), it would attempt to use new format first and fallback to the legacy format if needed. ([#105741](https://github.com/ku...

- The --leader-elect* CLI args are now honored correctly in scheduler. (#106130, @Huang-Wei) [SIG Scheduling]
- The kube-proxy sync_proxy_rules_iptables_total metric now gives
  the correct number of rules, rather than being off by one.
  
  Fixed multiple iptables proxy regressions introduced in 1.22:
  
    - When using Services with SessionAffinity, client affinity for an

## 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]