Anthropic Accidentally Exposes Claude Code Source Files

Anthropic accidentally published internal Claude Code source files on March 31, 2026, after an npm package included a map file that pointed to a zip archive on a Cloudflare R2 bucket. Security researcher Chaofan Shou and others downloaded roughly 1,900 TypeScript files (about 512,000 lines), which were mirrored and forked over 41,500 times on GitHub. Anthropic says it was human error, no customer data was exposed, and fixes are underway.
Key Points
- 1Exposes ~1,900 TypeScript files and 512,000+ lines via npm map file pointing to Cloudflare R2
- 2Reveals supply-chain and packaging risk, showing map files can leak internal source when published
- 3Suggests engineers must audit build pipelines, .npmignore and package.json to prevent similar leaks
Scoring Rationale
Confirmed same-day leak with strong evidence (public GitHub mirrors and company admission) raises novelty and actionability. Scope is primarily Anthropic but has broader supply-chain implications for developers, so score is high for immediacy and practical relevance.
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