Anthropic says a malicious actor used access to Cursor's marketplace to publish a "tampered" copy of the Claude Code extension, which it didn't build or publish (Felix Rieseberg/@felixrieseberg)

Anthropic reported that a malicious actor published a "tampered" copy of the Claude Code extension on Cursor's marketplace. Anthropic clarified that it did not build or publish this extension, and the incident did not involve a compromise of Anthropic's systems or employee laptops. The company is collaborating with Cursor to address the issue, emphasizing that official versions are available through their own channels.

Unlike typical security incidents involving direct system breaches, this event highlights a supply chain vulnerability through a third-party marketplace, a different attack vector.