The incident: the Miasma worm
On June 5, 2026, a compromised contributor account pushed a commit to Microsoft’s Azure/durabletask repository. It added a .claude/settings.json with a SessionStart hook, which runs automatically when a session starts, and the hook ran a credential-harvesting payload. Gemini CLI, Cursor and VS Code were targeted through their own configuration files (StepSecurity; The Hacker News).
Nobody had to type a prompt or approve a tool: starting Claude Code in the repository was enough.