Trojanized Claude Code extension appears in the Cursor marketplace

A malicious Claude Code IDE extension not built by Anthropic, anthropic.claude-code 2.1.313, appeared in the Cursor extension marketplace on October 29, 2026, and an estimated maximum of 5,000 users installed it before Cursor took it down. The build prepends a loader in extension.js that, when the IDE starts, collects the hostname, user, Git email, public IP and environment variables whose names match KEY|TOKEN|SECRET|PASS|AWS|GCP, writes the attacker's SSH public key into authorized_keys, establishes a persistent reverse SSH tunnel and installs persistence, then sends host information back to the C2 via port 8099. Netskope recommends that users who installed it, in addition to uninstalling the extension, check SSH keys, persistence files and tunnel processes and rotate credentials, and that the C2 IP 134.209.82[.]225 can be used to locate affected hosts in network events.