Intel / article

smolmachines / smolvm as a sandbox for untrusted Python & JavaScript

Source: simonwillison.net
Date: Published Aug 19, 2026

Context

The smolvm tests commissioned by developer Simon Willison examined whether untrusted Python and JavaScript transformations could run with bounded resources and restricted access. His report on version 1.8.3 says hardware-isolated virtual machines respected the tested network restrictions, memory and CPU limits, timeouts and separate input/output mounts.

The conducting the tests had to move execution to a hosted runner because its original container lacked the virtualization support required by smolvm. That requirement matters when choosing where to run the tool: having a container available does not establish that it can host these virtual machines. The results document specific controls in that test environment.

Terms in this piece · Glossary

AI agent — An AI system that doesn't just answer once but works toward a goal in a loop — taking actions, reading the results, and deciding what to do next.
eval — A repeatable test for AI quality — a set of tasks plus scoring — used the way software teams use test suites, because model output is too variable to judge by eyeballing.
sandbox — An isolated environment where AI-generated code or agent actions run without being able to touch anything real.

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