The official Claude Code for VS Code extension bundle contains a backdoor that establishes persistent SSH access across multiple operating systems.

"Phorion has detected a backdoor in the official Claude Code for VS Code extension bundle on Open VSX that drops a persistent SSH backdoor across macOS, Linux, and Windows. This write-up focuses primarily on macOS, where the extension attempts to configure an SSH backdoor and establish persistence. Organisations should immediately review their environments for use of Claude Code for VSCode 2.1.313 and engage incident response where use of the extension is discovered." https://phorion.io/blog/offical-claude-code-vsx-compromise/

Backdoor in Claude Code for VS Code extension on the Cursor Marketplace https://phorion.io/blog/offical-claude-code-vsx-compromise/ https://news.ycombinator.com/item?id=50300683

Official Claude Code Extension Compromise: Security Advisory October 30, 2026 TL;DR Phorion has detected a backdoor in the official Claude Code for VS Code extension bundle on the Cursor Marketplace https://phorion.io/blog/offical-claude-code-vsx-compromise/ #SSH_Backdoor #Cursor_Marketplace #VS_Code #macOS #Linux #Windows #Threat_Report