# CVE-2020-3221: Cisco IOS XE Software Flexible NetFlow Version 9 Denial of Service Vulnerability

> Remote attackers can cause a device reload by sending malformed Flexible NetFlow packets to Cisco Catalyst 9800 Wireless Controllers.

- **Severity:** High 8.6 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 3 Jun 2020
- **Updated:** 15 Nov 2024
- **Also known as:** GHSA-q65h-8wrc-fm43

## What is CVE-2020-3221?

CVE-2020-3221 is a high-severity denial of service vulnerability in Cisco Ios Xe, published on 3 Jun 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability in the Flexible NetFlow Version 9 packet processor of Cisco IOS XE Software for Cisco Catalyst 9800 Series Wireless Controllers could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to improper validation of parameters in a Flexible NetFlow Version 9 record. An attacker could exploit this vulnerability by sending a malformed Flexible NetFlow Version 9 packet to the Control and Provisioning of Wireless Access Points (CAPWAP) data port of an affected device. An exploit could allow the attacker to trigger an infinite loop, resulting in a process crash that would cause a reload of the device.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2020-3221?

It affects 1 product.


Products: Cisco Ios Xe.

## How do I fix CVE-2020-3221?

No fix has been published for CVE-2020-3221 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-3221 being exploited?

There is no known exploitation of CVE-2020-3221 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-2020-3221 and fix it if it is affected.

What it is: CVE-2020-3221 is a high-severity denial of service vulnerability in Cisco Ios Xe, published on 3 Jun 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2020-3221 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-2020-3221/ (Markdown: https://insights.sbomify.com/CVE-2020-3221/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-3221
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-3221
- OSV: https://osv.dev/vulnerability/CVE-2020-3221

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-3221/
Summaries are generated and may contain mistakes; the official description above is the record.