Cursor Removes Malicious Claude Code Extension

Cursor removed a malicious Claude Code extension from its marketplace after it was found to contain code designed to create persistent remote access to developers’ computers. The company said the modified version, 2.1.313, may have been accessed by at most 5,000 users. That figure is an exposure ceiling, not a confirmed count of installations or compromised machines. The extension was listed on October 29 for roughly 11 hours, from about 2:27 a.m. to 1:35 p.m. Pacific time, according to Cursor’s incident account. Cursor said the malicious version was not developed by Anthropic and that it had no evidence other versions or the official distribution were affected. The company said it would contact potentially affected users directly. A review of the package found a loader placed before the extension’s standard code. It was configured to add an attacker-controlled SSH key labelled “svctelemetry,” establish persistence and open a reverse SSH tunnel to a remote server. It could also send host details, including a computer’s name, username, operating system, public IP address and the names of environment variables that might indicate configured credentials. The initial transmission...