Container runtime security protects containerized workloads throughout their lifecycle by enforcing isolation, restricting privileges, and detecting threats. Containers share the host kernel, making the runtime layer—the interface between the kernel and container processes—a critical attack surface. Modern container security combines Linux kernel primitives (namespaces, cgroups, capabilities), mandatory access control systems (AppArmor, SELinux, BPF-LSM), and runtime monitoring tools to prevent escapes, privilege escalation, and lateral movement. As supply chain attacks and container breakouts intensify in 2026, teams must layer defense-in-depth controls from build to runtime, integrating image signing, vulnerability scanning, RBAC hardening, and behavior-based threat detection into every deployment.
What This Cheat Sheet Covers
This topic spans 16 focused tables and 95 indexed concepts. Below is a complete table-by-table outline of this topic, spanning foundational concepts through advanced details.
Table 1: User and Privilege Isolation
The most impactful container security wins come from running processes as non-root — both inside the container and on the host. These controls ensure that even a compromised container yields minimal host-level power to an attacker.
| Technique | Example | Description |
|---|---|---|
podman run --rm alpine whoami | • Containers run as a non-root user on the host • Docker daemon runs without root privileges, eliminating root-level attack surface entirely. | |
securityContext:runAsNonRoot: truerunAsUser: 1000 | • Kubernetes security context that forces containers to run as a non-root user • the pod fails to start if the image uses UID 0. | |
docker run --userns-remap=default nginx | • Maps container root (UID 0) to an unprivileged host user • even after a breakout, the attacker has no host root access — one of the most effective hardening mitigations. |