CVE-2026-20040 Cisco IOS XR Software CLI Privilege Escalation Vulnerability

High 8.8 Published 11 Mar 2026 Updated 12 Mar 2026

An authenticated local attacker can execute arbitrary commands as root on Cisco IOS XR devices due to insufficient CLI argument validation.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Local or same network only
Victim action needed: Not needed
Fix: None listed

What is CVE-2026-20040?

CVE-2026-20040 is a high-severity command injection vulnerability in Cisco Ios Xr, published on 11 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

A vulnerability in the CLI of Cisco IOS XR Software could allow an authenticated, local attacker to execute arbitrary commands as root on the underlying operating system of an affected device. This vulnerability is due to insufficient validation of user arguments that are passed to specific CLI commands. An attacker with a low-privileged account could exploit this vulnerability by using crafted commands at the prompt. A successful exploit could allow the attacker to elevate privileges to root and execute arbitrary commands on the underlying operating system.

Weakness: CWE-78

Which versions are affected by CVE-2026-20040?

It affects 1 product.

Products include Cisco Ios Xr.

How do I fix CVE-2026-20040?

No fix has been published for CVE-2026-20040 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-2026-20040 being exploited?

There is no known exploitation of CVE-2026-20040 in the wild and no public exploit code.

All Cisco Ios Xr vulnerabilities

Sources

Also known as GHSA-4x82-6phf-h73c.