Agentsstrong signal
Two Claude Code extension versions in Cursor's marketplace carried a backdoor
Versions 2.1.312 and 2.1.313 of Anthropic's Claude Code extension, served by Cursor's extension marketplace on October 29, plant an attacker's SSH key and try to keep a hidden tunnel open. Cursor says Anthropic did not build them. Removing the extension does not undo the damage, so Cursor has published a check and cleanup scripts.
Cursorverified