CVE-2026-40857

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

HIGH

8.4

CVSS Score

Published: September 16, 2026 at 11:21 AM UTC

Updated: September 28, 2026 at 11:10 PM UTC

1 product affected across 1 vendorT-Mobile 5G Box IDU

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Severity

HIGH8.4

Exploit prediction

EPSS 0.2%

SSVC

No known exploit

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

T-Mobile 5G Box IDU · Wnc

60%

v < 1.1.0.651412

Affected range stops below 1.1.0.651412, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

References (1)

Third Party Advisory

Source: cverecord

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

SSVC — Action Prioritization

SSVCNo known exploitNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

8.4HIGHCERT-PL

Vector?

Quick Info

StatusAWAITING ANALYSIS

CWE

CWE-352

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