AI Sec Watch: A Security Intelligence Platform for AI Systems

Luu, T.J.

Claude Code uses Bun written in Rust now

infonews

industry

Source: Simon Willison's WeblogJuly 18, 2026

Summary

Claude Code version 2.1.181 and later now use Bun (a JavaScript runtime and toolkit) rewritten in Rust instead of the original JavaScript version, which improved startup speed by 10% on Linux. The article provides technical evidence that this Rust-based version is running in production across millions of devices, though most users didn't notice the change.

Classification

Attack SophisticationTrivial

Affected Vendors

Anthropic

Related Issues

info

Secure AI agent access patterns to AWS resources using Model Context Protocol

Same vendorAWS Security Blog

high

Anthropic accuses Chinese AI labs of mining Claude as US debates AI chip exports

Same vendorTechCrunch

Monthly digest — independent AI security research

Original source: https://simonwillison.net/2026/Jul/19/claude-code-in-bun-in-rust/#atom-everything

First tracked: July 19, 2026 at 02:00 AM

Classified by LLM (prompt v3) · confidence: 75%