---
title: "Anthropic says a malicious actor used access to Cursor's marketplace to publish a \"tampered\" copy of the Claude Code extension, which it didn't build or publish (Felix Rieseberg/@felixrieseberg)"
type: signal
url: https://frontiernewswire.com/s/anthropic-says-a-malicious-actor-used-access-to-cursors-marketplace-to-45e77194
published: 2026-10-31T05:00:15.000Z
byline: "Source: TECHMEME"
---

# Anthropic says a malicious actor used access to Cursor's marketplace to publish a "tampered" copy of the Claude Code extension, which it didn't build or publish (Felix Rieseberg/@felixrieseberg)

Source: TECHMEME · Published 2026-10-31 · Canonical: https://frontiernewswire.com/s/anthropic-says-a-malicious-actor-used-access-to-cursors-marketplace-to-45e77194

Felix Rieseberg / @felixrieseberg : Anthropic says a malicious actor used access to Cursor's marketplace to publish a "tampered" copy of the Claude Code extension, which it didn't build or publish — 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 a...

In this story: [Anthropic](https://frontiernewswire.com/companies/anthropic), [Claude Code](https://frontiernewswire.com/models/claude-code), [Cursor](https://frontiernewswire.com/models/cursor)

## Sources

- [Read the original at TECHMEME](https://www.techmeme.com/261031/p2#a261031p2)

## Related on Frontier

- [Official Claude Code VS Code Extension Compromised to Install Persistent SSH Backdoor](https://frontiernewswire.com/s/official-claude-code-vs-code-extension-compromised-to-install-d53c08b0)
- [Devs Hit by Trojanized Claude Code Extension for Cursor](https://frontiernewswire.com/s/devs-hit-by-trojanized-claude-code-extension-for-cursor-2e3ddd3c)
- [Shadowy AI Relay Disables OpenAI Codex, Claude Code Sandboxes](https://frontiernewswire.com/s/shadowy-ai-relay-disables-openai-codex-claude-code-sandboxes-7f8e647a)
- [Claude Model Builds Exploits Across Major Browsers \& OSes](https://frontiernewswire.com/s/claude-model-builds-exploits-across-major-browsers-oses-3f7541f6)

---

[More Latest Signal](https://frontiernewswire.com/) · [Signals](https://frontiernewswire.com/verified-reporting)