CVE-2026-40857 PUBLISHED

CSRF token bypass 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 contains a cross-site request forgery (CSRF) vulnerability in the portal.cgi component. The anti-CSRF mechanism fails to validate the csrf_token_value parameter, accepting any arbitrary value as valid. This allows a remote attacker to perform unauthorized actions on the device by tricking an authenticated user into visiting a malicious website.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:A/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N
CVSS Score: 8.4

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

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-352 Cross-Site request forgery (CSRF) CWE