* The Kubelet's deprecated `--allow-privileged` flag now defaults to true. This enables users to stop setting `--allow-privileged` in order to transition to `PodSecurityPolicy`. Previously, users had to continue setting `--allow-privileged`, because the default was false. ([#63442](https://github.com/kubernetes/kubernetes/pull/63442), [@mtaufen](https://github.com/mtaufen))

  - go_gc_cycles_total_gc_cycles_total
  - go_gc_heap_allocs_by_size_bytes
  - go_gc_heap_allocs_bytes_total
  - go_gc_heap_allocs_objects_total
  - go_gc_heap_frees_by_size_bytes
  - go_gc_heap_frees_bytes_total
  - go_gc_heap_frees_objects_total
  - go_gc_heap_goal_bytes
  - go_gc_heap_objects_objects
  - go_gc_heap_tiny_allocs_objects_total
  - go_gc_pauses_seconds

The FSGroup's CSIDriver Policy is now beta in 1.20. This allows CSIDrivers to explicitly indicate if they want Kubernetes to manage permissions and ownership for their volumes via `fsgroup`. 

### Security Improvements for CSI Drivers (Alpha)

The feature to configure volume permission and ownership change policy for Pods moved to GA in 1.23.
This allows users to skip recursive permission changes on mount and speeds up the pod start up time.

### Allow CSI drivers to opt-in to volume ownership and permission change graduates to GA

The feature to allow CSI Drivers to declare support for fsGroup based permissions graduates to GA in 1.23.

### PodSecurity graduates to Beta

objects and send requests proxying through them.

Kubernetes supports node proxying, which allows clients of kube-apiserver to access endpoints of a Kubelet to establish connections to Pods, retrieve container logs, and more. While Kubernetes already validates the proxying address for Nodes, a bug in kube-apiserver made it possible to bypass this validation. Bypassing this validation could allow authenticated requests destined for Nodes to be redirected to the API Server through its private...

kube-controller manager now use SO_REUSEPORT socket option when listening on address defined by --bind-address and --secure-port flags, when running on Unix systems (Windows is NOT supported). This allows to run multiple instances of those processes on a single host with the same configuration, which allows to update/restart them in a graceful way, without causing downtime. ([#88893](https://github.com/kubernetes/kubernetes/pull/88893), [@invidian](https://github.com/invidian)) [SIG API Machinery, Scheduling...

# v1.5.5

This release contains a fix for a PodSecurityPolicy vulnerability which allows users to make use of any existing PodSecurityPolicy object, even ones they are not authorized to use.

Other then that, this release contains no other changes from 1.5.4.

- **Volume Extension**: There are quite a few enhancements in this release that pertain to volumes and volume modifications. Volume resizing support in CSI specs is moving to beta which allows for any CSI spec volume plugin to be resizable.

### Additional Notable Feature Updates

### Promoted Server Side Unknown Field Validation to Beta

Promoted the `ServerSideFieldValidation` feature gate to beta (on by default). This allows optionally triggering schema validation on the API server that errors when unknown fields are detected. This allows the removal of client-side validation from kubectl while maintaining the same core functionality of erroring out on requests that contain unknown or invalid fields.

objects and send requests proxying through them.

Kubernetes supports node proxying, which allows clients of kube-apiserver to access endpoints of a Kubelet to establish connections to Pods, retrieve container logs, and more. While Kubernetes already validates the proxying address for Nodes, a bug in kube-apiserver made it possible to bypass this validation. Bypassing this validation could allow authenticated requests destined for Nodes to be redirected to the API Server through its private...