// ClaudeHIGH
A compromised Claude Code extension (version 2.1.313) was published on Open VSX marketplace on October 29, 2026, containing an SSH backdoor that executed automatically upon installation. The malware established persistent reverse SSH tunnels, installed attacker SSH keys, and exfiltrated developer machine metadata and credential inventory. Up to 5,000 Cursor users were affected before the malicious version was removed after 11 hours. Cleanup requires manual removal of backdoor artifacts.
- Claude Code extension poisoned with persistent SSH backdoor - He(opens in a new tab)
- Official Claude Code Extension Compromise: Security Advisory | P(opens in a new tab)
- Hackers hijacked a Claude Code extension, exposing yet another n(opens in a new tab)
- Inside a malicious Claude Code-branded extension and its persist(opens in a new tab)
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