Anthropic: That Claude Code extension compromise… couldn't be us

A tampered Claude Code extension distributed through Cursor’s marketplace infected up to 5,000 developers and exposed host details while attempting to install persistence and a reverse SSH tunnel, underscoring how quickly trusted developer tools can become supply-chain attack vectors. For CIOs and technology leaders, the incident highlights the need to treat AI coding extensions and marketplace-delivered software as high-risk dependencies, with stronger vendor governance, rapid revocation/replacement processes, and better detection for compromised developer environments. IT teams should expect that simply updating software may not remove a threat and should be prepared to hunt for persistence, rotate credentials/keys, and validate the integrity of all developer toolchains.