OpenAI adds MXC-based sandbox mode to Codex on Windows

OpenAI announced on October 9, 2026 that it has built a new sandbox mode for Codex on Windows using Microsoft's Execution Containers (MXC). The mode aims to provide faster setup, stronger network enforcement, and granular file access controls, and requires a compatible Windows 11 device.

Codex is OpenAI's AI coding assistant for developers.