# CVE-2021-1435: Cisco IOS XE Software Web UI Command Injection Vulnerability

> Authenticated attackers can inject arbitrary commands into the Cisco IOS XE web UI to execute code with root privileges.

- **Severity:** Medium 6.6 (`CVSS:3.0/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 24 Mar 2021
- **Updated:** 16 Dec 2025
- **Also known as:** GHSA-5rv2-fphg-fgcg

## What is CVE-2021-1435?

CVE-2021-1435 is a medium-severity command injection vulnerability in Cisco Ios Xe, published on 24 Mar 2021. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

A vulnerability in the web UI of Cisco IOS XE Software could allow an authenticated, remote attacker to inject arbitrary commands that can be executed as the root user. This vulnerability is due to insufficient input validation. An attacker could exploit this vulnerability by sending a crafted request to the web UI of an affected device with arbitrary commands injected into a portion of the request. A successful exploit could allow the attacker to execute arbitrary commands as the root user.

Weakness: CWE-22 (Improper Limitation of a Pathname to a Restricted Directory)

## Which versions are affected by CVE-2021-1435?

It affects 1 product.


Products: Cisco Ios Xe.

## How do I fix CVE-2021-1435?

No fix has been published for CVE-2021-1435 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-1435 being exploited?

There is no known exploitation of CVE-2021-1435 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-2021-1435 and fix it if it is affected.

What it is: CVE-2021-1435 is a medium-severity command injection vulnerability in Cisco Ios Xe, published on 24 Mar 2021. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-1435 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-2021-1435/ (Markdown: https://insights.sbomify.com/CVE-2021-1435/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-1435
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-1435
- OSV: https://osv.dev/vulnerability/CVE-2021-1435

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-1435/
Summaries are generated and may contain mistakes; the official description above is the record.