# CVE-2021-1230: Cisco Nexus 9000 Series Fabric Switches ACI Mode BGP Route Installation Denial of Service Vulnerability

> An unauthenticated remote attacker can crash the routing process on Cisco Nexus 9000 switches in ACI mode by sending a crafted BGP update, causing a device reload.

- **Severity:** High 8.6 (`CVSS:3.1/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:** 24 Feb 2021
- **Updated:** 8 Nov 2024
- **Also known as:** GHSA-5hv8-h736-6fwx

## What is CVE-2021-1230?

CVE-2021-1230 is a high-severity denial of service vulnerability in Cisco Nx-Os, published on 24 Feb 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability with the Border Gateway Protocol (BGP) for Cisco Nexus 9000 Series Fabric Switches in Application Centric Infrastructure (ACI) mode could allow an unauthenticated, remote attacker to cause a routing process to crash, which could lead to a denial of service (DoS) condition. This vulnerability is due to an issue with the installation of routes upon receipt of a BGP update. An attacker could exploit this vulnerability by sending a crafted BGP update to an affected device. A successful exploit could allow the attacker to cause the routing process to crash, which could cause the device to reload. This vulnerability applies to both Internal BGP (IBGP) and External BGP (EBGP). Note: The Cisco implementation of BGP accepts incoming BGP traffic from explicitly configured peers only. To exploit this vulnerability, an attacker would need to send a specific BGP update message over an established TCP connection that appears to come from a trusted BGP peer.

Weakness: CWE-233 (Improper Handling of Parameters)

## Which versions are affected by CVE-2021-1230?

It affects 1 product.


Products: Cisco Nx-Os.

## How do I fix CVE-2021-1230?

No fix has been published for CVE-2021-1230 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-1230 being exploited?

There is no known exploitation of CVE-2021-1230 in the wild and no public exploit code.

## Other vulnerabilities in Cisco Nx-Os

- [CVE-2024-20399](https://insights.sbomify.com/CVE-2024-20399/): Cisco NX-OS Command Injection (medium 6.0, exploited in the wild)
- [CVE-2021-1361](https://insights.sbomify.com/CVE-2021-1361/): Cisco NX-OS Software Unauthenticated Arbitrary File Actions Vulnerability (critical 9.8)
- [CVE-2018-0301](https://insights.sbomify.com/CVE-2018-0301/): Memory corruption in Cisco NX-OS unknown (critical 9.8)
- [CVE-2016-1453](https://insights.sbomify.com/CVE-2016-1453/): Memory corruption in n/a (critical 9.8)
- [CVE-2016-1341](https://insights.sbomify.com/CVE-2016-1341/): Hardcoded credentials in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-1230 and fix it if it is affected.

What it is: CVE-2021-1230 is a high-severity denial of service vulnerability in Cisco Nx-Os, published on 24 Feb 2021. 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-2021-1230 in the wild and no public exploit code.

Affected product: Cisco Nx-Os. 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-2021-1230/ (Markdown: https://insights.sbomify.com/CVE-2021-1230/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-1230
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-1230
- OSV: https://osv.dev/vulnerability/CVE-2021-1230

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-1230/
Summaries are generated and may contain mistakes; the official description above is the record.