Cursor says tampered Claude Code versions 2.1.312 and 2.1.313 for macOS and Windows sent host information and installed attacker SSH keys and persistence scripts. They were distributed on October 29 from approximately 09:27 to 20:35 UTC, or 18:27 KST October 29 to 05:35 KST October 30. Permission limits and code errors could prevent SSH activation, but did not mean information transmission or leftover components were absent. Cursor blocked the malicious distribution and server and advises isolating affected hosts, removing unauthorized keys and processes, and rotating credentials from a trusted device. Anthropic says its official distribution channels were unaffected.