What is Kubernetes security?

Kubernetes security encompasses the practices, tools, and configurations used to protect Kubernetes clusters, workloads, and data. It includes authentication, authorization (RBAC), network policies, pod security standards, secrets management, and runtime security.

What is the CKS certification?

The Certified Kubernetes Security Specialist (CKS) is a CNCF certification that validates expertise in securing Kubernetes clusters. It covers cluster setup and hardening, system hardening, minimizing microservice vulnerabilities, and supply chain security.

What are Kubernetes network policies?

Network policies are Kubernetes resources that control pod-to-pod and pod-to-external traffic. They act as a firewall for your cluster, allowing you to specify which pods can communicate with each other based on labels, namespaces, and ports.

What are Pod Security Standards?

Pod Security Standards (PSS) are predefined security profiles that define different levels of pod security restrictions: Privileged (unrestricted), Baseline (minimally restrictive to prevent known privilege escalations), and Restricted (heavily restricted following security best practices).

What is RBAC in Kubernetes?

Role-Based Access Control (RBAC) is a Kubernetes authorization mechanism that regulates access to resources based on user roles. It uses Role, ClusterRole, RoleBinding, and ClusterRoleBinding resources to define and assign permissions to users and service accounts.

How do I secure etcd in Kubernetes?

Secure etcd by enabling encryption at rest for secrets, using TLS for client-server communication, restricting access to etcd endpoints via firewall rules, enabling authentication, and running regular backups. etcd stores all cluster data including secrets.

What is a container escape attack?

A container escape attack occurs when a process breaks out of container isolation to access the host system or other containers. Common vectors include privileged containers, hostPath mounts, and kernel exploits. Mitigate with Pod Security Standards and seccomp profiles.

What tools are used for Kubernetes security scanning?

Popular Kubernetes security tools include Trivy (vulnerability scanning), Falco (runtime security), kube-bench (CIS benchmarks), OPA Gatekeeper and Kyverno (policy enforcement), Kubescape (security posture), and Cosign (image signing).

CVE-2023-5528 — Windows node privilege escalation via in-tree storage plugin

HIGH7.2CVE-2023-5528

CVSS vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
Affected projects: kubernetes
Disclosed: November 14, 2023
Last updated: April 30, 2026

Affected versions

Project	Vulnerable range
kubelet	`>= v1.8.0`

Patched versions

Project	Fixed in
kubelet	`v1.28.4`
kubelet	`v1.27.8`
kubelet	`v1.26.11`
kubelet	`v1.25.16`

References

Summary

A security issue was discovered in Kubernetes where a user with the ability to create pods and persistent volumes on Windows nodes may be able to escalate to admin privileges on those nodes. Kubernetes clusters are only affected if they are using an in-tree storage plugin for Windows nodes. Any Kubernetes environment with Windows nodes running kubelet v1.8.0 or later is impacted.

Impact

An attacker with the ability to create pods and PersistentVolumes on Windows nodes can exploit insufficient input sanitization in the in-tree storage plugin to escalate privileges to administrator on those nodes. Successful exploitation results in high impact to confidentiality, integrity, and availability on affected Windows nodes. Clusters without Windows nodes are not affected. There are no known mitigations outside of applying the provided patch.

Detection

Check whether your cluster includes Windows nodes:

kubectl get nodes -l kubernetes.io/os=windows

Review Kubernetes audit logs for PersistentVolume create events that include local path fields containing special characters. Such events are a strong indicator of exploitation attempts.

If evidence of exploitation is found, contact security@kubernetes.io.

Mitigation

Upgrade kubelet to one of the fixed versions:

v1.28.4 or later (1.28 branch)
v1.27.8 or later (1.27 branch)
v1.26.11 or later (1.26 branch)
v1.25.16 or later (1.25 branch)

There are no known alternative mitigations outside of applying the patch. Refer to the Kubernetes cluster upgrade documentation for upgrade guidance.

Affected versions

Patched versions

References

Summary​

Impact​

Detection​

Mitigation​

References​

Summary

Impact

Detection

Mitigation

References