If You Code in Cursor and Updated Claude Code on Oct. 29, Run This One Check
A tampered copy sat in Cursor's marketplace for about 11 hours and tried to plant an SSH backdoor. It wasn't made by Anthropic.
By Dez Marlowe ·
Cursor, the AI coding company, says a malicious version of the Claude Code extension, versions 2.1.312 and 2.1.313 for Mac and Windows, was up in its marketplace from about 2:27 a.m. to 1:35 p.m. Pacific time on Oct. 29. Cursor says Anthropic didn't make it.
The fake version grabbed info about your computer and tried to add the attacker's SSH key, labeled svc-telemetry, so they could get back in. Cursor says the remote tunnel usually failed, but the key and the background scripts could still be there. Uninstalling may not remove them.
Cursor shut down its marketplace, rebuilt it, rotated keys and got the attacker's server taken offline.
Check: search your ~/.ssh/authorized_keys file for svc-telemetry. If it's there, follow Cursor's cleanup steps and change your passwords and tokens from a different, clean computer.
What we still don't know: how the attacker got the upload in, and how many people installed it.
Sources
Dez Marlowe is a Boston Uncut reporter covering Boston, Massachusetts, national and world news.