Sync-in Server is an open-source platform for file storage, sharing, collaboration, and syncing. Prior to version 2.4.0, POST /api/auth/token authenticates with username and password only, then calls getTokens(), which returns full access and refresh JWTs without checking whether the account has TOTP 2FA enabled. An attacker with stolen or phished credentials can bypass 2FA in a single request. The parallel login endpoint (POST /api/auth/login) correctly enforces 2FA by calling setCookies(user, res, true), which gates on user.twoFaEnabled. Version 2.4.0 patches the issue.