Methodology for Assessing Kubernetes Namespace-Based Multi-Tenancy Setups

Thu, 26 Mar 2026 00:00:00 +0000

This page introduces our structured methodology for assessing security risks in Kubernetes environments that use Namespace-based Multi-Tenancy. It addresses weaknesses that break Namespace-based isolation that not well studied, yet. We found this issues during our research and presented them together with this methodology in our Talk at KubeCon + CloudNativeCon Europe 2026.

The methodology assumes that industry best practices, such as NetworkPolicies, Role-Based Access Control (RBAC), and Pod Security Standards, are already in place. These measures provide a necessary baseline level of protection against well-known isolation threats. However, they are insufficient to address a class of more subtle attack vectors arising from interactions between tenants and shared components. Such attack vectors may still compromise the confidentiality, integrity, and availability (CIA) of the cluster and its workloads, even in well-hardened environments.

Security Considerations on Istio’s CRDs with Namespace-based Multi-Tenancy

Wed, 25 Mar 2026 00:00:00 +0000

We reported a possible Man-in-the-Middle (MitM) attack scenario in which a VirtualService can redirect or intercept traffic within the service mesh. This affects Namespace-based Multi-Tenancy clusters where tenants have the permissions to deploy Istio resources (networking.istio.io/v1).

In collaboration with Istio, we published a guest submission in Istio’s blog (as well as below), a Security Bulletin, and an update to their Security Model to address this issue.

This blog post highlights the risks of using Istio in multi-tenant clusters and explains how users can mitigate these risks and safely operate Istio in their deployments.

Multi-Tenancy on Insinuator.net - Bold Statements

Methodology for Assessing Kubernetes Namespace-Based Multi-Tenancy Setups

Security Considerations on Istio’s CRDs with Namespace-based Multi-Tenancy