Skip to main content
cve.nowby Sazabi
Early warnings
SZB-244b3755f3

Malicious Claude Code VS Code extension was distributed via Cursor marketplace, per BleepingComputer

Status
Corroborated, not yet confirmed by the vendor
Kind
Malicious package
Vendor
Anthropic
Product
Claude Code VS Code extension
First seen

Summary

BleepingComputer reports that a malicious version of Anthropic's Claude Code VS Code extension was available through Cursor's extension marketplace for about 11 hours on October 29. It says up to 5,000 developers may have been exposed to malware designed to install persistent SSH backdoors.

If you use Anthropic

Check whether the Claude Code extension in Cursor or VS Code was installed or updated on October 29

Uninstall the extension and reinstall it only from the official publisher listing

Review authorized SSH keys and recent SSH logins on developer machines

Rotate SSH keys and credentials stored on any machine that installed the extension

Check Anthropic's official channels for any advisory about Claude Code compromise before relying on this report

Verify the installed Claude Code version and update only from official Anthropic sources

Timeline

  1. Made public by Kevin Beaumont on Bluesky1 day
  2. First seen by cve.now1 day
  3. Record last updated

What the sources say 7

· Kevin Beaumont on Bluesky: “New by me - Anthropic have been hacked to deliver remote access malware to millions of endpoints who use Claude Code.” Source

· BleepingComputer on Bluesky: “A malicious version of Anthropic's Claude Code VS Code extension was distributed through Cursor's extension marketplace for approximately 11 hours on October 29, exposing up to 5,000 developers to malware designed to install persistent SSH backdoors.” Source

· Bluesky: “Security notice — malicious version of claude code (2.1.312 and 2.1.313) identified in the Cursor VS Code Extension Marketplace” Source

· Mastodon: “backdoor in the official Claude Code for VS Code extension bundle on the Cursor Marketplace that drops a persistent SSH backdoor across macOS, Linux, and Windows.” Source

· Mastodon: “Thanks to a lucky break, flawed code in a tainted Claude extension prevented the attacker from fully worming their way into some 5,000 developer machines.” Source

· Mastodon: “The tampered Claude Code extension planted an attacker’s SSH key that uninstalling may not remove.” Source

· Mastodon: “Anthropic VS code extension on Cursor backdoored for nearly 12 hours” Source