"Official Claude Code Extension Compromise: Security Advisory"

News is making the rounds today that Claude Code has been compromised. What appears to be the official VS Code extension for Claude Code creates a persistent SSH backdoor. That’s bad.

One wrinkle is that the bad extension seems not to appear on the official Microsoft “Marketplace”¹ but only on the one for Cursor, the pseudo-trivial VS Code fork that was somehow worth a hojillion dollars.

My initial reaction, probably like many people’s, was that Anthropic was compromised, something I am still anticipating. Strongly anticipating.

But according to Felix Rieseberg on Hacker News, it seems Cursor, the pseudo-trivial VS Code sellout, is to blame:

Felix from Anthropic here.

We’re working with Cursor on this incident, but it wasn’t a compromise of Anthropic’s systems or employee laptops. A malicious actor used access to Cursor’s marketplace to publish a tampered copy of the Claude Code extension, which we didn’t build or publish. The versions on our official channels are not affected and this only impacts Cursor users.

Not surprised about Cursor. Secure the bag and run.

https://phorion.io/blog/offical-claude-code-vsx-compromise/

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1. What a dumb name for a website listing of extensions, by the way. ↩︎