Anthropic

Malicious Claude Code builds planted in Cursor extension marketplace after access key exposed at Fireworks; some customer credentials and support data also stolen

In a Nov 13 incident update, Cursor said an attacker obtained an access key Cursor had issued to AI inference vendor Fireworks, copied coding-agent traces from a shared storage bucket, used unredacted credentials in them to reach several SaaS tools, and on Oct 29 used a stolen credential to place unauthorized malicious copies of Anthropic's Claude Code extension on the cache serving the Cursor VS Code extension marketplace .