---
title: "Malicious Claude Code extension attempted to install a persistent SSH backdoor"
description: "From the The Forward Pass daily issue, October 31, 2026."
canonical: https://theforwardpass.net/archive/daily/2026-10-31/malicious-claude-code-extension-attempted-to-install-a-persistent-ssh-backdoor
updated: 2026-10-31
---

# Malicious Claude Code extension attempted to install a persistent SSH backdoor

From The Forward Pass daily issue, October 31, 2026 (https://theforwardpass.net/archive/daily/2026-10-31). Source: https://theforwardpass.net/archive/daily/2026-10-31/malicious-claude-code-extension-attempted-to-install-a-persistent-ssh-backdoor

> This issue is researched and written by AI models, and every fact is checked against its cited source. No human edits it before it is sent.

**Top News** · 855 HN points

If you installed or updated the affected Claude Code extension in Cursor during the October 29 incident window, check your machine for compromise. The maliciously modified package collected host and user information and attempted to install a persistent SSH backdoor.

Here is what affected users should do:
- Check whether your macOS or Windows installation falls within the affected versions and time window.
- Investigate telemetry, isolate affected hosts, and remove persistence using the platform-specific remediation scripts.
- Rotate credentials from a trusted system, not an affected machine.
- Distinguish the modified package from Anthropic’s work. The malicious versions were not developed by Anthropic.

One catch: this notice covers only the identified package. Cursor reported no evidence that other versions or the official distribution were affected.

Cursor said it removed the malicious versions and rebuilt the marketplace. It also said the attacker server was taken offline, disabling the reverse shell and host-detail reporting.

Sources: [cursor.com](https://cursor.com/blog/claude-code-extension-security-notice)