# CVE-2026-40857: WNC T-Mobile 5G Box IDU CSRF in portal.cgi

Source: https://junglewise.ai/threats/cve-2026-40857-wnc-t-mobile-5g-box-idu-csrf-in-portal-cgi  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-16. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-40857 · Severity: info · Published 2026-09-16

The WNC T-Mobile 5G Box IDU router's web administration interface fails to properly validate anti-CSRF tokens, allowing an attacker to trick an authenticated administrator into performing unauthorized actions on the device via a malicious website. An attacker could modify router settings, change network configuration, or compromise connected devices without the administrator's knowledge or consent.

Technologies: [WNC T-Mobile 5G Box IDU](https://junglewise.ai/threats/technologies/t-mobile-5g-box-idu). Vendors: [WNC](https://junglewise.ai/threats/vendors/wnc).

## Quick answers

**Is CVE-2026-40857 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-40857 being exploited in the wild.

**How severe is CVE-2026-40857?** Informational severity, published 16 September 2026.

**Which products and versions are affected?** WNC T-Mobile 5G Box IDU before 1.1.0.651412.

**Is there a fix for CVE-2026-40857?** A patch was published on 2026-09-16: firmware version 1.1.0.651412 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-40857 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-40857?** Check whether you run WNC T-Mobile 5G Box IDU at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

This is a cross-site request forgery (CSRF) vulnerability in the portal.cgi component of the router's web interface. The anti-CSRF protection mechanism accepts any arbitrary value for the csrf_token_value parameter without proper validation, failing to prevent forged requests from untrusted origins. Attack requires an authenticated user (administrator) to be currently logged into the router and to visit an attacker-controlled website. An attacker can perform any action the logged-in user has permission to perform, such as modifying device configuration, updating settings, or creating new accounts. The vulnerability has been patched in firmware version 1.1.0.651412 and later.

## Affected products

- WNC T-Mobile 5G Box IDU before 1.1.0.651412

## Timeline

- 2026-09-16: disclosed
- 2026-09-16: patched: firmware version 1.1.0.651412

## References

- [https://cert.pl/posts/2026/09/CVE-2026-40854](https://cert.pl/posts/2026/09/CVE-2026-40854)

## Related threats

- [WNC T-Mobile 5G Box IDU OS command injection in password change](https://junglewise.ai/threats/cve-2026-58147-wnc-t-mobile-5g-box-idu-os-command-injection-in-password-change)
- [WNC T-Mobile 5G Box IDU OS command injection in portal.cgi](https://junglewise.ai/threats/cve-2026-58146-wnc-t-mobile-5g-box-idu-os-command-injection-in-portal-cgi)
- [WNC T-Mobile 5G Box IDU improper access control in wnc_maccheck.cgi](https://junglewise.ai/threats/cve-2026-40856-wnc-t-mobile-5g-box-idu-improper-access-control-in-wnc-maccheck)
- [WNC T-Mobile 5G Box IDU command injection in ping functionality](https://junglewise.ai/threats/cve-2026-40855-wnc-t-mobile-5g-box-idu-command-injection-in-ping-functionality)
- [WNC T-Mobile 5G Box IDU authentication bypass in portal.cgi](https://junglewise.ai/threats/cve-2026-40854-wnc-t-mobile-5g-box-idu-authentication-bypass-in-portal-cgi)