Kubernetes namespaces are widely used by developers and infrastructure maintainers to group resources within clusters, yet their role as pivotal security boundaries often gets overlooked.

Many well-established and upcoming Kubernetes features rely on secure namespace management, from in-cluster DNS resolution to Network Policies, Limit Ranges, Pod Security Standards, and Gateway API Cross-Namespace Routing.

The talk will investigate the implications of compromise within a cluster if an adversary successfully tampers existing namespaces or crafts new ones by delving into real-world use cases, including multi-tenancy and cluster-native policy enforcement.

A spectrum of mitigations and best practices to lock down namespaces effectively will be presented, covering strategies from Role-Based Access Control (RBAC) to advanced object validation using admission controllers, including secure approaches with namespace templating in multi-tenant environments.