# CVE-2019-1840: Cisco Prime Network Registrar Denial of Service Vulnerability

> Remote attackers can cause a denial of service by sending malformed DHCPv6 packets if custom extensions are installed to modify packets before sanitization.

- **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:** 18 Apr 2019
- **Updated:** 19 Nov 2024
- **Also known as:** GHSA-788r-rf8c-vgj3

## What is CVE-2019-1840?

CVE-2019-1840 is a high-severity denial of service vulnerability in Cisco Prime Network Registrar, published on 18 Apr 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability in the DHCPv6 input packet processor of Cisco Prime Network Registrar could allow an unauthenticated, remote attacker to restart the server and cause a denial of service (DoS) condition on the affected system. The vulnerability is due to incomplete user-supplied input validation when a custom extension attempts to change a DHCPv6 packet received by the application. An attacker could exploit this vulnerability by sending malformed DHCPv6 packets to the application. An exploit could allow the attacker to trigger a restart of the service which, if exploited repeatedly, might lead to a DoS condition. This vulnerability can only be exploited if the administrator of the server has previously installed custom extensions that attempt to modify the packet details before the packet has been processed. Note: Although the CVSS score matches a High SIR, this has been lowered to Medium because this condition will only affect an application that has customer-developed extensions that will attempt to modify packet parameters before the packet has been completely sanitized. If packet modification in a custom extension happens after the packet has been sanitized, the application will not be affected by this vulnerability. Software versions prior to 8.3(7) and 9.1(2) are affected.

Weakness: CWE-665 (Improper Initialization)

## Which versions are affected by CVE-2019-1840?

It affects 1 product.


Products: Cisco Prime Network Registrar.

## How do I fix CVE-2019-1840?

No fix has been published for CVE-2019-1840 yet. Limit exposure of the affected software until one is available.

## Is CVE-2019-1840 being exploited?

There is no known exploitation of CVE-2019-1840 in the wild and no public exploit code.

## Other vulnerabilities in Cisco Prime Network Registrar

- [CVE-2020-3272](https://insights.sbomify.com/CVE-2020-3272/): Cisco Prime Network Registrar DHCP Denial of Service Vulnerability (high 7.5)
- [CVE-2016-1427](https://insights.sbomify.com/CVE-2016-1427/): Information disclosure in n/a (high 7.5)
- [CVE-2015-6296](https://insights.sbomify.com/CVE-2015-6296/): Hardcoded credentials in n/a (high 7.2)
- [CVE-2020-3148](https://insights.sbomify.com/CVE-2020-3148/): Cisco Prime Network Registrar Cross-Site Request Forgery Vulnerability (high 7.1)
- [CVE-2017-6613](https://insights.sbomify.com/CVE-2017-6613/): Denial of service in Cisco Prime Network Registrar (medium 5.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2019-1840 and fix it if it is affected.

What it is: CVE-2019-1840 is a high-severity denial of service vulnerability in Cisco Prime Network Registrar, published on 18 Apr 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-2019-1840 in the wild and no public exploit code.

Affected product: Cisco Prime Network Registrar. 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-2019-1840/ (Markdown: https://insights.sbomify.com/CVE-2019-1840/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-1840
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-1840
- OSV: https://osv.dev/vulnerability/CVE-2019-1840

---
From sbomify Insights: https://insights.sbomify.com/CVE-2019-1840/
Summaries are generated and may contain mistakes; the official description above is the record.