# CVE-2021-34721: Cisco IOS XR Software Command Injection Vulnerabilities

> Authenticated local attackers can exploit CLI vulnerabilities to gain root shell access and execute arbitrary commands on Cisco IOS XR devices.

- **Severity:** Medium 6.7 (`CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 9 Sep 2021
- **Updated:** 7 Nov 2024
- **Also known as:** GHSA-9r24-f9qq-w8p5

## What is CVE-2021-34721?

CVE-2021-34721 is a medium-severity command injection vulnerability in Cisco Ios Xr, published on 9 Sep 2021. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Multiple vulnerabilities in the CLI of Cisco IOS XR Software could allow an authenticated, local attacker to gain access to the underlying root shell of an affected device and execute arbitrary commands with root privileges. For more information about these vulnerabilities, see the Details section of this advisory.

Weakness: CWE-78 (Improper Neutralization of Special Elements used in an OS Command)

## Which versions are affected by CVE-2021-34721?

It affects 1 product.


Products: Cisco Ios Xr.

## How do I fix CVE-2021-34721?

No fix has been published for CVE-2021-34721 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-34721 being exploited?

There is no known exploitation of CVE-2021-34721 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-2021-34721 and fix it if it is affected.

What it is: CVE-2021-34721 is a medium-severity command injection vulnerability in Cisco Ios Xr, published on 9 Sep 2021. 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-2021-34721 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-2021-34721/ (Markdown: https://insights.sbomify.com/CVE-2021-34721/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-34721
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-34721
- OSV: https://osv.dev/vulnerability/CVE-2021-34721

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-34721/
Summaries are generated and may contain mistakes; the official description above is the record.