Containers Aren't a Real Security Boundary: Kata Containers and Firecracker Urged for Sandboxes

andreamichi · x · 2026-09-25

Security folks are debating whether containers have ever served as a genuine security boundary. The quoted take: if escaping or moving laterally requires a bug to build a primitive, a boundary exists to cross — RCE inside a K8s pod doesn't mean you control the node. Containers may be a weak boundary, but the boundary is real.

The poster adds that judging by how many sandbox startups rely purely on containers, the industry overestimates container isolation, and recommends Kata Containers and Firecracker as a better immediate security alternative (microVM-grade isolation) — directly relevant for agent sandboxing and code-execution infrastructure.

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