Isolation Techniques: Namespaces, cgroups, and Sandboxing

Containers share a kernel. Every isolation boundary between your workload and the host is a Linux kernel feature that can be misconfigured, weakened, or bypassed. The previous article covered security controls and frameworks: Gatekeeper, Kyverno, Falco, CIS Benchmarks. Those tools enforce policies. But the actual isolation boundaries they protect are kernel primitives: namespaces, cgroups, seccomp filters, and user identity mappings.

This article covers the mechanisms that make container isolation work, where they fall short, and what to reach for when kernel-shared isolation isn't enough. If you're preparing for the KCSA, this maps directly to the "Isolation Techniques" subtopic in the Cloud Native Security domain (14%).