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

CVE-2026-40855Command Injection in T-Mobile 5G Box IDU router via ping functionality

Critical 9.3

In plain English

A critical-severity OS command injection 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 1.6% (higher than 76% of all known vulnerabilities).

Severity (CVSS 4.0)9.3Critical

Exploit odds (30 days)1.6%top 24.2% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

WNC T-Mobile 5G Box IDU router is vulnerable to a command injection. The vulnerability exists in the ping functionality within the /cgi-bin/portal.cgi endpoint, specifically affecting the ping_ip, ping_size, and ping_times POST parameters. The root cause is the failure to verify and sanitize user-supplied input before incorporating it into a system command. This allows an authenticated attacker to execute arbitrary commands on the shell and gain root access to the system.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-78 · Vector: CVSS:4.0/AV:A/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

References

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