# CVE-2021-1390: Cisco IOS XE Software Local Privilege Escalation Vulnerability

> An authenticated local attacker with high privileges can exploit a diagnostic command logic error to execute arbitrary code on the underlying OS.

- **Severity:** Medium 5.1 (`CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:H/A:N`)
- **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:** 24 Mar 2021
- **Updated:** 8 Nov 2024
- **Also known as:** GHSA-587f-4vmq-c6m5

## What is CVE-2021-1390?

CVE-2021-1390 is a medium-severity vulnerability in Cisco Ios Xe, published on 24 Mar 2021. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A vulnerability in one of the diagnostic test CLI commands of Cisco IOS XE Software could allow an authenticated, local attacker to execute arbitrary code on an affected device. To exploit this vulnerability, the attacker would need to have valid user credentials at privilege level 15. This vulnerability exists because the affected software permits modification of the run-time memory of an affected device under specific circumstances. An attacker could exploit this vulnerability by authenticating to the affected device and issuing a specific diagnostic test command at the CLI. A successful exploit could trigger a logic error in the code that was designed to restrict run-time memory modifications. The attacker could take advantage of this logic error to overwrite system memory locations and execute arbitrary code on the underlying Linux operating system (OS) of the affected device.

Weakness: CWE-123 (Write-what-where Condition)

## Which versions are affected by CVE-2021-1390?

It affects 1 product.


Products: Cisco Ios Xe.

## How do I fix CVE-2021-1390?

No fix has been published for CVE-2021-1390 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-1390 being exploited?

There is no known exploitation of CVE-2021-1390 in the wild and no public exploit code.

## Other vulnerabilities in Cisco Ios Xe

- [CVE-2023-20198](https://insights.sbomify.com/CVE-2023-20198/): Cisco IOS XE Web UI Privilege Escalation (critical 10.0, exploited in the wild)
- [CVE-2018-0151](https://insights.sbomify.com/CVE-2018-0151/): Cisco IOS Software and Cisco IOS XE Software Quality of Service Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2023-20273](https://insights.sbomify.com/CVE-2023-20273/): Cisco IOS XE Web UI Command Injection (high 7.2, exploited in the wild)
- [CVE-2025-20188](https://insights.sbomify.com/CVE-2025-20188/): Hardcoded credentials in Cisco IOS XE Software (critical 10.0)
- [CVE-2021-34770](https://insights.sbomify.com/CVE-2021-34770/): Cisco IOS XE Software for Catalyst 9000 Family Wireless Controllers CAPWAP Remote Code Execution Vulnerability (critical 10.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-1390 and fix it if it is affected.

What it is: CVE-2021-1390 is a medium-severity vulnerability in Cisco Ios Xe, published on 24 Mar 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-2021-1390 in the wild and no public exploit code.

Affected product: Cisco Ios Xe. 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-2021-1390/ (Markdown: https://insights.sbomify.com/CVE-2021-1390/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-1390
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-1390
- OSV: https://osv.dev/vulnerability/CVE-2021-1390

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-1390/
Summaries are generated and may contain mistakes; the official description above is the record.