Cursor identified malicious versions of the Claude Code extension, 2.1.312 and 2.1.313, for macOS and Windows that were available through its marketplace between about 2:27 a.m. and 1:35 p.m. PT on October 29, 2026. The payload attempted to add an attacker-controlled SSH key, enable remote access and establish a reverse tunnel, while persistence mechanisms could remain after the extension was uninstalled. Successful remote access depended on the machine’s SSH configuration and permissions, with a permission-check bug preventing the macOS code from automatically enabling remote login when run by a standard user. Cursor recommends isolating compromised machines, removing unauthorized SSH keys, persistence mechanisms and tunnels, then rotating accessible credentials and sessions from a trusted system. No cryptocurrency theft or crypto-specific targeting has been established.
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