GoKawiilCursor says breach via Fireworks AI credential led to malicious Claude Code extension
Cursor disclosed that attackers stole an access key stored at third-party provider Fireworks AI and used it to pull data from a shared storage bucket containing historical AI coding-agent traces. Some traces had unredacted API credentials, which attackers then used to breach other Cursor systems and push malicious versions of Anthropic's Claude Code extension through Cursor's marketplace on October 29, exposing up to 5,000 developers to malware installing SSH backdoors. Cursor says fewer than 0.05% of users had traces exposed and fewer than 0.01% had credentials compromised.