TGstation is a toolset to manage production BYOND servers. In affected versions if a Windows user was registered in tgstation-server (TGS), an attacker could discover their username by brute-forcing the login endpoint with an invalid password. When a valid Windows logon was found, a distinct response would be generated. This issue has been addressed in version 5.12.5. Users are advised to upgrade. Users unable to upgrade may be mitigated by rate-limiting API calls with software that sits in front of TGS in the HTTP pipeline such as fail2ban.
