- Pods were allowed to use the `net.ipv4.tcp_rmem` and `net.ipv4.tcp_wmem` sysctl by default
  when the kernel version was 4.15 or higher. With the kernel 4.15 the sysctl became namespaced.

* The `spec.SecurityContext.Sysctls` field is now dropped during creation of `Pod` objects unless the `Sysctls` feature gate is enabled. ([#72752](https://github.com/kubernetes/kubernetes/pull/72752), [@rajathagasthya](https://github.com/rajathagasthya))
    * The `spec.AllowedUnsafeSysctls` and `spec.ForbiddenSysctls` fields are now dropped during creation of `PodSecurityPolicy` objects unless the `Sysctls` feature gate is enabled.

  
  When the feature gate is enabled, kubelet ignores errors that happens during setting the following sysctl values: `vm.overcommit_memory`, `vm.panic_on_oom`, `kernel.panic`, `kernel.panic_on_oops`, `kernel.keys.root_maxkeys`, `kernel.keys.root_maxbytes`. (These sysctl values for the host, not for the containers)
  
  kubelet also ignores an error during opening `/dev/kmsg`.

- Sysctls graduates to General Availability and thus unconditionally enabled. ([#99158](https://github.com/kubernetes/kubernetes/pull/99158), [@wgahnagl](https://github.com/wgahnagl))

- Kubelet allows pods to use the `net.ipv4.ip_local_reserved_ports` sysctl by default and the minimal kernel version is 3.16; Pod Security admission allows this sysctl in v1.27+ versions of the baseline and restricted policies. ([#115374](https://github.com/kubernetes/kubernetes/pull/115374), [@pacoxu](https://github.com/pacoxu)) [SIG Auth, Network and Node]

	VMV4RV		V8, V4				// 57b2819e
	VMV8RV		V8, V0				// 57b0839e

	//
	// Privileged ISA
	//

	// 3.3.1: Environment Call and Breakpoint
	ECALL						// 73000000
	SCALL						// 73000000
	EBREAK						// 73001000
	SBREAK						// 73001000

	// Arbitrary bytes (entered in little-endian mode)
	WORD	$0x12345678	// WORD $305419896	// 78563412

### Promoted SeccompDefault to Beta

SeccompDefault promoted to beta, see the tutorial [Restrict a Container's Syscalls with seccomp](https://kubernetes.io/docs/tutorials/security/seccomp/#enable-the-use-of-runtimedefault-as-the-default-seccomp-profile-for-all-workloads) for more details.

### Promoted endPort in Network Policy to Stable

* Fix how we iterate over active jobs when removing them for Replace policy ([#36161](https://github.com/kubernetes/kubernetes/pull/36161), [@soltysh](https://github.com/soltysh))
* Adds TCPCloseWaitTimeout option to kube-proxy for sysctl nf_conntrack_tcp_timeout_time_wait ([#35919](https://github.com/kubernetes/kubernetes/pull/35919), [@bowei](https://github.com/bowei))

- Introduced the flag `--ipvs-strict-arp` to configure stricter ARP sysctls, defaulting to false to preserve existing behaviors. This was enabled by default in 1.13.0, which impacted a few CNI plugins. ([#75295](https://github.com/kubernetes/kubernetes/pull/75295), [@lbernail](https://github.com/lbernail))

* [IPVS] Allow for transparent kube-proxy restarts ([#75283](https://github.com/kubernetes/kubernetes/pull/75283), [@lbernail](https://github.com/lbernail))
* [IPVS] Introduces flag ipvs-strict-arp to configure stricter ARP sysctls, defaulting to false to preserve existing behaviors. This was enabled by default in 1.13.0, which impacted a few CNI plugins. ([#75295](https://github.com/kubernetes/kubernetes/pull/75295), [@lbernail](https://github.com/lbernail))