{"data":{"id":"4a14244a-45ac-40a0-8e19-2549be68f45c","title":"Claude Code uses Bun written in Rust now","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.","solution":"N/A -- no mitigation discussed in source.","labels":["industry"],"sourceUrl":"https://simonwillison.net/2026/Jul/19/claude-code-in-bun-in-rust/#atom-everything","publishedAt":"2026-07-19T03:54:09.000Z","cveId":null,"cweIds":null,"cvssScore":null,"cvssSeverity":null,"severity":"info","attackType":[],"issueType":"news","affectedPackages":null,"affectedVendors":["Anthropic"],"affectedVendorsRaw":["Anthropic","Claude Code","Bun"],"classifierModel":"claude-haiku-4-5-20251001","classifierPromptVersion":"v3","cvssVector":null,"attackVector":null,"attackComplexity":null,"privilegesRequired":null,"userInteraction":null,"exploitMaturity":null,"epssScore":null,"patchAvailable":null,"disclosureDate":"2026-07-19T03:54:09.000Z","capecIds":null,"crossRefCount":0,"attackSophistication":"trivial","impactType":null,"aiComponentTargeted":null,"llmSpecific":false,"classifierConfidence":0.75,"researchCategory":null,"atlasIds":null}}