# CVE-2020-3397: Cisco NX-OS Software Border Gateway Protocol Multicast VPN Denial of Service Vulnerability

> Remote attackers can cause a denial of service on Cisco NX-OS devices by sending crafted BGP MVPN messages, requiring peer trust information.

- **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:** 27 Aug 2020
- **Updated:** 13 Nov 2024
- **Also known as:** GHSA-5799-w2pr-v9hg

## What is CVE-2020-3397?

CVE-2020-3397 is a high-severity denial of service vulnerability in Cisco Nx-Os, published on 27 Aug 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability in the Border Gateway Protocol (BGP) Multicast VPN (MVPN) implementation of Cisco NX-OS Software could allow an unauthenticated, remote attacker to cause an affected device to unexpectedly reload, resulting in a denial of service (DoS) condition. The vulnerability is due to incomplete input validation of a specific type of BGP MVPN update message. An attacker could exploit this vulnerability by sending this specific, valid BGP MVPN update message to a targeted device. A successful exploit could allow the attacker to cause one of the BGP-related routing applications to restart multiple times, leading to a system-level restart. Note: The Cisco implementation of BGP accepts incoming BGP traffic from only explicitly configured peers. To exploit this vulnerability, an attacker must send a specific BGP MVPN update message over an established TCP connection that appears to come from a trusted BGP peer. To do so, the attacker must obtain information about the BGP peers in the trusted network of the affected system.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2020-3397?

It affects 1 product.


Products: Cisco Nx-Os.

## How do I fix CVE-2020-3397?

No fix has been published for CVE-2020-3397 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-3397 being exploited?

There is no known exploitation of CVE-2020-3397 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-2020-3397 and fix it if it is affected.

What it is: CVE-2020-3397 is a high-severity denial of service vulnerability in Cisco Nx-Os, published on 27 Aug 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-2020-3397 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-2020-3397/ (Markdown: https://insights.sbomify.com/CVE-2020-3397/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-3397
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-3397
- OSV: https://osv.dev/vulnerability/CVE-2020-3397

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-3397/
Summaries are generated and may contain mistakes; the official description above is the record.