Malicious Claude Code extension with SSH backdoor was live on Cursor marketplace for 11 hours
MALWAREAnthropicredteam/daily · 2 sources
- Severity
- High
- Sources
- 2
What happened
Cursor confirmed that malicious Anthropic.claude-code versions 2.1.312 and 2.1.313 were available through the VS Code Extension Marketplace from about 2:27 a.m. to 1:35 p.m. Pacific Time on 29 October 2026. The payload collected host and user details, added an attacker-controlled SSH key labelled svc-telemetry, and tried to open a reverse SSH tunnel, though errors and missing admin rights limited most login attempts. Cursor removed the packages, rotated its keys, rebuilt the marketplace and disabled the attacker's server, and found no other extensions altered.
For IT people · Written by AI from 2 sources · Wrong?
What to do
- Check whether Anthropic.claude-code versions 2.1.312 or 2.1.313 are installed and remove them.
- Inspect authorised SSH keys for an entry labelled svc-telemetry and remove it if found.
- Review extension installation records, endpoint alerts and network logs for the indicators Cursor published.
- Isolate affected hosts where payload execution or backdoor installation is evident, then rotate accessible credentials and sessions from a trusted system.
Written by AI from the sources, checked against them
Full story timeline · 2 updates
Who reported · 2 outlets
Cyber Security NewsCSO Online
Who and what is in it
Products