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

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

- **Severity:** High 8.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 11 Mar 2026
- **Updated:** 12 Mar 2026
- **Also known as:** GHSA-4x82-6phf-h73c

## 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 (Improper Neutralization of Special Elements used in an OS Command)

## Which versions are affected by CVE-2026-20040?

It affects 1 product.


Products: 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.

## Is CVE-2026-20040 being exploited?

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

## Other vulnerabilities in Cisco Ios Xr

- [CVE-2020-3118](https://insights.sbomify.com/CVE-2020-3118/): Cisco IOS XR Software Discovery Protocol Format String (high 8.8, exploited in the wild)
- [CVE-2020-3569](https://insights.sbomify.com/CVE-2020-3569/): Cisco IOS XR Software DVMRP Memory Exhaustion (high 8.6, exploited in the wild)
- [CVE-2020-3566](https://insights.sbomify.com/CVE-2020-3566/): Cisco IOS XR Software DVMRP Memory Exhaustion (high 8.6, exploited in the wild)
- [CVE-2010-3035](https://insights.sbomify.com/CVE-2010-3035/): Cisco IOS XR Border Gateway Protocol (BGP) Denial-of-Service (high 7.5, exploited in the wild)
- [CVE-2022-20821](https://insights.sbomify.com/CVE-2022-20821/): Cisco IOS XR Open Port (medium 6.5, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-20040 and fix it if it is affected.

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

Affected product: Cisco Ios Xr. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-20040/ (Markdown: https://insights.sbomify.com/CVE-2026-20040/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-20040
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-20040
- OSV: https://osv.dev/vulnerability/CVE-2026-20040

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-20040/
Summaries are generated and may contain mistakes; the official description above is the record.