# A Supply Chain Attack Put Malicious Anthropic Claude Extensions on Thousands of Devices

- URL: https://talkfuse.com/story/a-supply-chain-attack-put-malicious-anthropic-claude-extensions-on-thousands-of-devices/
- Published: 2026-10-30T20:38:46+00:00
- Updated: 2026-10-30T21:53:22+00:00
- Original publisher: Wired
- Original article: https://www.wired.com/story/trojan-malware-targets-thousands-of-anthropic-claude-developer-systems/
- Topics: AI, Americas, Software, Technology, World

## Key points

- A malicious Claude Code extension was available on Cursor for about 11 hours.
- Up to 5,000 users may have downloaded it.
- Anthropic said its systems were not compromised.

## Summary

Cursor’s extension marketplace hosted a malicious copy of the Claude Code extension for about 11 hours on Thursday, exposing up to 5,000 users to a backdoor that could give attackers access to their devices. The incident matters because such access can provide a foothold for further attacks within a target network, although a flaw in the malware prevented it from fully establishing itself on most devices.

Cursor temporarily closed the marketplace while investigating and published remediation steps; it said other extensions were unaffected. Anthropic said its systems and staff devices were not compromised, and that the tampered extension was neither built nor published by the company. How the malicious upload reached Cursor’s marketplace remains unclear.

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Summarised by TalkFuse (https://talkfuse.com/). Quote the original publisher for the reporting and link this page for the summary and discussion.