Cursor discloses a trojanized Claude Code extension that planted an SSH backdoor on up to 5,000 developers
AspireAI community · Cursor
A tampered Claude Code extension reached up to 5,000 developers through Cursor's marketplace and planted an SSH backdoor.
Versions 2.1.312 and 2.1.313 of anthropic.claude-code, served from Cursor's marketplace between about 2:27am and 1:35pm PT on October 29, appended an attacker key labeled svc-telemetry to your authorized_keys, tried to enable the local SSH service, and set up persistence retrying a reverse tunnel every 60s. It also posted hostname, username, OS, Git email and public IP, plus names of up to 40 environment variables that look like keys. Cursor says Anthropic did not build the package, the attacker server is offline, and the fix is 2.1.314.
The honest limit: enabling SSH needs admin rights, so on most machines that step failed. The key, the persistence and the beacon did not.
https://cursor.com/blog/claude-code-extension-security-notice
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