Cursor says around 5,000 people may have installed a malicious Claude Code extension.

The SpaceX-owned AI coding tool says the modified version of Claude Code appeared on its extension marketplace from 5:27AM ET and 4:35PM ET on Thursday. The extension contains malicious code that collects various information, including hostname, username, operating system, home directory path, public IP address, and more.

Cursor says around 5,000 people may have installed a malicious Claude Code extension.

TL;DR

  • A malicious version of the Claude Code extension was available on the Cursor marketplace.
  • The extension was active on Thursday between 5:27 AM ET and 4:35 PM ET.
  • It contained malicious code designed to collect user information like hostname, username, OS, home directory path, and public IP address.
  • Cursor has removed the malicious extension and verified the security of other extensions.