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-2021-25745 — Ingress-nginx path field can expose service account token

HIGH7.6CVE-2021-25745

CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:L
Affected projects: kubernetes
Disclosed: April 22, 2022
Last updated: April 30, 2026

Affected versions

Project	Vulnerable range
ingress-nginx	`< v1.2.0`

Patched versions

Project	Fixed in
ingress-nginx	`v1.2.0-beta.0`
ingress-nginx	`v1.2.0`

References

Summary

A security issue in ingress-nginx allows a user with permission to create or update Ingress objects to use the spec.rules[].http.paths[].path field of an Ingress object in the networking.k8s.io or extensions API group to obtain the credentials of the ingress-nginx controller. By crafting the path value to reference the controller's service account token file, the attacker retrieves the token. In the default configuration, that credential has access to all secrets in the cluster.

Impact

Any user who can create or update Ingress objects in a cluster running ingress-nginx prior to v1.2.0 can exploit this vulnerability to read the ingress-nginx service account token directly. Because the default service account has cluster-wide access to secrets, the effective impact is full read access to all Kubernetes secrets in the cluster. Multitenant environments where non-admin users hold Ingress create or update permissions are most at risk.

Detection

Audit which users and service accounts hold the create or update verbs on networking.k8s.io/ingresses or extensions/ingresses, and inspect Ingress objects for path values that reference filesystem paths. If you find evidence that this vulnerability has been exploited, contact security@kubernetes.io.

Mitigation

Upgrade ingress-nginx to v1.2.0 (or the release candidate v1.2.0-beta.0) or later, which adds sanitization of the path field to block references to sensitive files.

If an immediate upgrade is not possible, implement an admission policy that restricts the spec.rules[].http.paths[].path field on networking.k8s.io/Ingress resources to a known safe character set. The ingress-nginx project documents a suggested annotation-value-word-blocklist ConfigMap setting that provides a reference blocklist pattern for this purpose.

Affected versions

Patched versions

References

Summary​

Impact​

Detection​

Mitigation​

References​

Summary

Impact

Detection

Mitigation

References