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), 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, and behavior-based threat detection into every deployment.