# CVE-2019-1967: Cisco NX-OS Software Network Time Protocol Denial of Service Vulnerability

> Remote attackers can cause denial of service on Cisco NX-OS devices by flooding them with Mode 7 NTP packets, leading to high resource usage and system reloads.

- **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:** 29 Aug 2019
- **Updated:** 19 Nov 2024
- **Also known as:** GHSA-hvq8-fxqh-36fv

## What is CVE-2019-1967?

CVE-2019-1967 is a high-severity denial of service vulnerability in Cisco Nx-Os, published on 29 Aug 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability in the Network Time Protocol (NTP) feature of Cisco NX-OS Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to excessive use of system resources when the affected device is logging a drop action for received MODE_PRIVATE (Mode 7) NTP packets. An attacker could exploit this vulnerability by flooding the device with a steady stream of Mode 7 NTP packets. A successful exploit could allow the attacker to cause high CPU and memory usage on the affected device, which could cause internal system processes to restart or cause the affected device to unexpectedly reload. Note: The NTP feature is enabled by default.

Weakness: CWE-400 (Uncontrolled Resource Consumption), CWE-399

## Which versions are affected by CVE-2019-1967?

It affects 1 product.


Products: Cisco Nx-Os.

## How do I fix CVE-2019-1967?

No fix has been published for CVE-2019-1967 yet. Limit exposure of the affected software until one is available.

## Is CVE-2019-1967 being exploited?

There is no known exploitation of CVE-2019-1967 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-2019-1967 and fix it if it is affected.

What it is: CVE-2019-1967 is a high-severity denial of service vulnerability in Cisco Nx-Os, published on 29 Aug 2019. 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-2019-1967 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-2019-1967/ (Markdown: https://insights.sbomify.com/CVE-2019-1967/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-1967
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-1967
- OSV: https://osv.dev/vulnerability/CVE-2019-1967

---
From sbomify Insights: https://insights.sbomify.com/CVE-2019-1967/
Summaries are generated and may contain mistakes; the official description above is the record.