CVE-2026-40855 Command Injection in T-Mobile 5G Box IDU router via ping functionality
An authenticated attacker can execute arbitrary commands and gain root access via the ping functionality in the T-Mobile 5G Box IDU router.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-40855?
CVE-2026-40855 is a critical command injection vulnerability in WNC T-Mobile 5G Box IDU, published on 16 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
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
Weakness: CWE-78
Which versions are affected by CVE-2026-40855?
How do I fix CVE-2026-40855?
No fix has been published for CVE-2026-40855 yet. Limit exposure of the affected software until one is available.
Upgrade, and pass arguments to programs as a list instead of through a shell. More about Command injection.
Is CVE-2026-40855 being exploited?
There is no known exploitation of CVE-2026-40855 in the wild and no public exploit code.
Sources
Also known as GHSA-5qwp-rxmm-2vwh.