# CVE-2023-20169: Denial of service in Cisco NX-OS Software

> An unauthenticated adjacent attacker can cause a denial of service by sending crafted IS-IS packets to Cisco Nexus switches, triggering a device reload.

- **Severity:** High 7.4 (`CVSS:3.1/AV:A/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:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 23 Aug 2023
- **Updated:** 2 Aug 2024
- **Also known as:** GHSA-rjhj-97m9-mffq

## What is CVE-2023-20169?

CVE-2023-20169 is a high-severity denial of service vulnerability in Cisco Nx-Os, published on 23 Aug 2023. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A vulnerability in the Intermediate System-to-Intermediate System (IS-IS) protocol of Cisco NX-OS Software for the Cisco Nexus 3000 Series Switches and Cisco Nexus 9000 Series Switches in standalone NX-OS mode could allow an unauthenticated, adjacent attacker to cause the IS-IS process to unexpectedly restart, which could cause an affected device to reload.

 This vulnerability is due to insufficient input validation when parsing an ingress IS-IS packet. An attacker could exploit this vulnerability by sending a crafted IS-IS packet to an affected device. A successful exploit could allow the attacker to cause a denial of service (DoS) condition due to the unexpected restart of the IS-IS process, which could cause the affected device to reload. Note: The IS-IS protocol is a routing protocol. To exploit this vulnerability, an attacker must be Layer 2 adjacent to the affected device.

Weakness: CWE-20 (Improper Input Validation), CWE-788 (Access of Memory Location After End of Buffer)

## Which versions are affected by CVE-2023-20169?

It affects 1 product.


Products: Cisco Nx-Os.

## How do I fix CVE-2023-20169?

No fix has been published for CVE-2023-20169 yet. Limit exposure of the affected software until one is available.

## Is CVE-2023-20169 being exploited?

There is no known exploitation of CVE-2023-20169 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-2023-20169 and fix it if it is affected.

What it is: CVE-2023-20169 is a high-severity denial of service vulnerability in Cisco Nx-Os, published on 23 Aug 2023. 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-2023-20169 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-2023-20169/ (Markdown: https://insights.sbomify.com/CVE-2023-20169/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-20169
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-20169
- OSV: https://osv.dev/vulnerability/CVE-2023-20169

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-20169/
Summaries are generated and may contain mistakes; the official description above is the record.