CVE-2026-40856 PUBLISHED

Config disclosure in T-Mobile 5G Box IDU routers

Assigner: CERT-PL
Reserved: 15.04.2026 Published: 16.09.2026 Updated: 16.09.2026

WNC T-Mobile 5G Box IDU router is vulnerable to improper access control. The vulnerability exists in the wnc_maccheck.cgi endpoint, which is accessible without authentication. It allows a remote attacker to retrieve sensitive configuration data, including the administrator web password, WiFi passphrase, and technical device information.This issue has been fixed in firmware version 1.1.0.651412

Metrics

CVSS 4.0

CVSS Vector: CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
CVSS Score: 7.1

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Adjacent	Confidentiality	High	Confidentiality	None
Attack Complexity	Low	Integrity	None	Integrity	None
Attack Requirements	None	Availability	None	Availability	None
Privileges Required	None
User Interaction	None

CVSS 4.0

Product Status

Vendor	WNC
Product	T-Mobile 5G Box IDU
Versions	Default: unaffected affected from 0 to 1.1.0.651412 (excl.)

Credits

Patryk Bogdan finder
Adam Borczyk finder

References

https://cert.pl/posts/2026/09/CVE-2026-40854

Problem Types

CWE-306 Missing authentication for critical function CWE