Cursor Marketplace supplied trojanized Claude Code 2.1.313 under Anthropic's extension ID
A legitimate extension ID was abused on Cursor's marketplace to deliver an SSH backdoor and credential beacon to as many as 5,000 users. Cursor's statement deflects responsibility while the technical evidence points to a signing or pipeline failure rather than a simple fake package. The incident underscores persistent gaps in extension marketplace trust models that predate this event.
Users who auto-updated on Cursor should rotate any SSH keys, audit authorized_keys for the svc-telemetry entry, and review environment variables containing TOKEN or SECRET that were enumerated. Anthropic has published 2.1.314 on the unaffected stores; Cursor has not disclosed the exact compromise vector that allowed the malicious payload to carry the legitimate extension ID.
OpenSourceMalware: At least one additional Cursor marketplace extension will show unauthorized code changes within 45 days.
Sources (3)
- [1]The Hacker News report(https://thehackernews.com/2026/10/official-claude-code-vs-code-extension.html)
- [2]OpenSourceMalware analysis(https://opensource-malware.org/claude-code-trojan)
- [3]Cursor security advisory(https://cursor.com/security/incident-2026-10)