CVE-2026-28778: Hardcoded FTP Credentials and LPE(via Insecure Permissions) for `xd` Local Account on IDC SFX2100

International Datacasting Corporation (IDC) SFX Series SuperFlex Satellite Receiver contains undocumented, hardcoded/insecure credentials for the `xd` user account. A remote unauthenticated attacker can log in via FTP using these credentials. Because the `xd` user has write permissions to their home directory where root-executed binaries and symlinks (such as those invoked by `xdstartstop`) are stored, the attacker can overwrite these files or manipulate symlinks to achieve arbitrary code execution as the root user.