Vulnerability · Published Sep 16, 2026 · Assigned by CERT-PL

CVE-2026-40857CSRF token bypass in T-Mobile 5G Box IDU routers

High 8.4

In plain English

A high-severity cross-site request forgery in T-Mobile 5G Box IDU from WNC. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 9% of all known vulnerabilities).

Severity (CVSS 4.0)8.4High

Exploit odds (30 days)0.2%top 90.6% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

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

Affected products (as reported)

Vendor	Product	Versions
WNC	T-Mobile 5G Box IDU	0 – before 1.1.0.651412

Weakness: CWE-352 · 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

References

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