Tampered Claude Code extension on Cursor's marketplace tried to plant an SSH backdoor, hitting up to 5,000 users

Thu, Oct 29 20:00 UTC+8

Cursor said a tampered Anthropic.claude-code 2.1.313, not built by Anthropic, was on its extension marketplace for about 11 hours on Oct 29. It collected host details, added an attacker SSH key and tried to open a persistent reverse tunnel, though enabling SSH fails on most Macs and Windows PCs without admin rights. Up to 5,000 users were affected; Cursor pulled it and published cleanup scripts.

Why it matters

AI coding extensions run directly on developer machines, and this shows extension marketplaces are now a supply-chain entry point for attacks on developers.

Sources1

CursorMediaThu, Oct 29 20:00 UTC+8Security notice — malicious version of Anthropic.claude-code (2.1.313) identified in the Cursor Extension MarketplaceView original · Thu, Oct 29 20:00 UTC+8

Written by dalao.ai: the title, summary and why it matters are our own words. The original reports are the record; their publishers keep authorship.