637 npm Packages Compromised in 39 Minutes. The Malware Installs a Claude Code SessionStart Hook.
A sophisticated worm infected 637 npm packages within 39 minutes on May 19, 2026, affecting approximately 16 million weekly downloads. The malware, originating from a compromised npm account, not only exfiltrated credentials from cloud environments and developer tools but also exploited GitHub Actions to gain further npm publish access, enabling self-propagation. Notably, the attack targeted developer environments by installing hooks in tools like Claude Code and VS Code, and included a dead man's switch to delete user files if stolen tokens were revoked. AI
IMPACT This attack highlights the evolving threat landscape for AI development tools and the software supply chain.