A reported coding-extension backdoor persists beyond uninstalling

Phorion reports a backdoor in Claude Code for VS Code version 2.1.313 distributed through Cursor’s marketplace. The injected code runs when loaded, plants SSH keys and persistence, and attempts a reverse tunnel. Its macOS logic can fail to enable SSH when it was off, but still leaves malicious artifacts. Uninstalling the extension alone therefore does not remove the reported persistence.

Phorion · Oct 30, 2026

Why it matters

Developer extensions run with access to source files and local credentials, making package provenance part of workstation security.

More context

The October 30 investigation provides a sample hash, key fingerprints and platform-specific artifacts. Teams that used the affected version should preserve evidence and follow incident response covering keys, startup entries and running processes, rather than merely reinstalling a clean package.

Keep in mind

The analysis focuses on macOS and identifies implementation failures on other paths. It does not establish that every installation led to attacker login, nor does it prove all similarly numbered packages were compromised.

Original read