Coding & agents New
Cursor says a tampered Claude Code extension in its marketplace planted an SSH backdoor on up to 5,000 machines
Published:
Cursor, the AI coding editor owned by SpaceX, published a security notice dated 29 October. It says a maliciously modified Anthropic.claude-code version 2.1.313 was available in its own VS Code extension marketplace from about 2:27am to 1:35pm Pacific time that day. Cursor says the version was not developed by Anthropic and that at most 5,000 users were affected; it will contact them directly.
According to Cursor, the code collects host and user details, adds an attacker's SSH key labelled svc-telemetry to the user's authorized keys, installs persistence and tries to open a reverse SSH tunnel. Cursor says turning on the SSH service fails on most macOS and Windows machines because it needs administrator rights, but the key, the persistence and the host report still go through. Uninstalling the extension may not be enough, it says, and it publishes a check and removal scripts.
Cursor says it removed the version, shut down and rebuilt the marketplace, rotated its keys, audited access and found no other tampered extensions, and had the attacker's server taken offline. The Hacker News reports that the package was shipped under the extension's legitimate ID, that there is no evidence it reached Open VSX or Microsoft's marketplace, and that Anthropic has published version 2.1.314 to both.
Caveat. How the attacker got the package into Cursor's marketplace has not been explained, and no statement from Anthropic was found. The 5,000 figure is Cursor's upper bound.
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