Tinycontrol devices such as tcPDU and LAN Controllers LK3.5, LK3.9 and LK4 have two separate authentication mechanisms - one solely for interface management and one for protecting all other server resources. When the latter is turned off (which is a default setting), an unauthenticated attacker on the local network can obtain usernames and encoded passwords for interface management portal by inspecting the HTTP response of the server when visiting the login page, which contains a JSON file with these details. Both normal and admin users credentials are exposed. This issue has been fixed in firmware versions: 1.36 (for tcPDU), 1.67 (for LK3.5 - hardware versions: 3.5, 3.6, 3.7 and 3.8), 1.75 (for LK3.9 - hardware version 3.9) and 1.38 (for LK4 - hardware version 4.0).
Weakness
The code transmits data to another actor, but a portion of the data includes sensitive information that should not be accessible to that actor.
Potential Mitigations
- Compartmentalize the system to have “safe” areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area.
- Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.
Related Attack Patterns
- https://cwe.mitre.org/data/definitions/12.html
- https://cwe.mitre.org/data/definitions/217.html
- https://cwe.mitre.org/data/definitions/612.html
- https://cwe.mitre.org/data/definitions/613.html
- https://cwe.mitre.org/data/definitions/618.html
- https://cwe.mitre.org/data/definitions/619.html
- https://cwe.mitre.org/data/definitions/621.html
- https://cwe.mitre.org/data/definitions/622.html
- https://cwe.mitre.org/data/definitions/623.html
References
- https://cert.pl/en/posts/2026/03/CVE-2025-11500/
- https://securitum.com/CVE-2025-11500
- https://tinycontrol.pl/en/archives/lan-controller-35/downloads/#firmware
- https://tinycontrol.pl/en/lk39/downloads/#firmware
- https://tinycontrol.pl/en/lk4/downloads/#firmware
- https://tinycontrol.pl/en/tcpdu/downloads/#firmware