GCVE-110-OSM-2026-14303

The official Claude Code extension on the Cursor Marketplace has been compromised, and a threat actor published version 2.1.313. This malicious extension only affects the Cursor version of the extension and not any other registry version of it. The payload installed a persistent SSH based backdoor and RAT like functionality.1. Added an attacker-controlled key labeled svc-telemetry to ~/.ssh/authorized_keys. 2. Attempted to enable the machine’s SSH service or macOS Remote Login. 3. Opened a persistent reverse SSH tunnel to 134.209.82.225, forwarding the victim’s local SSH port. 4. Installed persistence: • macOS: fake com.apple.sysmond LaunchAgent • Linux: @reboot cron entry • Windows: SysMon scheduled task or Startup-folder fallback 5. Collected hostname, username, platform, architecture, home directory, working directory, Git email, public IP, and names of environment variables suggesting credentials. 6. Sent that reconnaissance as JSON to 134.209.82.225:8099/beacon. 7. Suppressed errors so the legitimate extension continued operating normally.