# CVE-2026-40855: WNC T-Mobile 5G Box IDU command injection in ping functionality

Source: https://junglewise.ai/threats/cve-2026-40855-wnc-t-mobile-5g-box-idu-command-injection-in-ping-functionality  
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-2026-40855 · Severity: info · Published 2026-09-16

The WNC T-Mobile 5G Box IDU is a 5G router device used by T-Mobile customers to provide broadband connectivity. The ping function in the router's web interface fails to validate user input, allowing an authenticated attacker to inject and execute arbitrary shell commands with root privileges, potentially compromising the device and any network it protects.

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-2026-40855 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-40855 being exploited in the wild.

**How severe is CVE-2026-40855?** Informational severity, published 16 September 2026.

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

**Is there a fix for CVE-2026-40855?** A patch was published on 2026-09-16: firmware version 1.1.0.651412 released Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-40855 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-40855?** 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 an OS command injection vulnerability (CWE-78) in the /cgi-bin/portal.cgi endpoint, specifically affecting the ping_ip, ping_size, and ping_times POST parameters. The root cause is insufficient input validation and sanitization before these parameters are passed to system commands. An authenticated attacker can inject shell metacharacters to break out of the intended command and execute arbitrary commands with root privileges. The vulnerability requires authentication to exploit but allows full system compromise. The vendor released firmware version 1.1.0.651412 to address this issue.

## Affected products

- WNC T-Mobile 5G Box IDU all versions before 1.1.0.651412

## Timeline

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

## 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 CSRF in portal.cgi](https://junglewise.ai/threats/cve-2026-40857-wnc-t-mobile-5g-box-idu-csrf-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 authentication bypass in portal.cgi](https://junglewise.ai/threats/cve-2026-40854-wnc-t-mobile-5g-box-idu-authentication-bypass-in-portal-cgi)