Cursor disclosed that a malicious build of the Anthropic Claude Code extension was distributed through its VS Code extension marketplace on Thursday, October 29, between approximately 2:27 a.m. and 1:35 p.m. Pacific. Its English notice names version 2.1.313; a parallel Cursor notice also identifies 2.1.312, so inspect either version if installed. The malicious package was not made by Anthropic. Cursor says it removed the package, rebuilt the marketplace and disabled the attacker’s server. This is an unusually relevant security bulletin because Cursor is part of your day-to-day development workflow.

The payload attempted to collect host details, add an attacker-controlled SSH public key, and establish persistent remote access. Cursor says several of the remote-access steps often failed without elevated privileges, but warns that uninstalling the extension alone may not remove separately written persistence files. The fact that the attacker server is down does not substitute for checking a potentially affected Mac.

Cursor’s official Mac check is: `grep -qs svc-telemetry ~/.ssh/authorized_keys && echo "svc-telemetry key found" || echo "No key found; machine not impacted"`. Run it on each Mac that could have received the extension. This is a narrow indicator check, not a universal malware scan. Also inspect Cursor’s Extensions panel for the affected version and source.

If the marker is present, follow Cursor’s full isolation and cleanup procedure from a trusted environment, then consider credential and session rotation. Do not paste private keys or credentials into an AI chat. If you did not install or update that extension during the specified window, the alert is mainly a useful reminder to treat editor extensions as executable code.

For the longer term, prefer verified distribution channels, keep a short inventory of installed extensions, and make a weekly audit of editor extensions part of the same maintenance rhythm as your Mac mini services. The immediate task is small: check two Macs, not launch a general security overhaul.

Additional details — https://prod.cursor.com/blog/claude-code-extension-security-notice | Go to Source — https://cursor.com/blog/claude-code-extension-security-notice