Microsoft LiteBox: Rust-Based Library OS Offers Container-to-VM Middle Ground for AI Agent Code Sandboxing

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Microsoft open-sourced LiteBox in February 2026 — a Rust-built Library OS with a POSIX-style North interface and a pluggable South interface that can target Linux, Windows, or SEV-SNP hardware. It runs unmodified Linux binaries inside a drastically reduced host attack surface, lighter than a full VM but with far fewer exposed syscalls than standard containers. Built in Rust for memory safety by construction. Still experimental (APIs unstable), but represents the emerging consensus that shared-kernel containers are insufficient for executing untrusted AI-generated code.