CVE-2019-1840

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of service disruption.

Exploit odds

2.4% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2019-04-18 02:29 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 02:29 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 2.4% in the next 30 days (EPSS).
• Severity: 8.6 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2019-04-18 02:29 UTC

Last modified

2026-06-17 02:29 UTC

Exploit probability

2.4% · EPSS, next 30 days

Weakness

CWE-665

Record status

Modified

Affected

• Cisco Prime Network Registrar < 8.3.7
• Cisco Prime Network Registrar < 9.1.2

Attack profile CVSS 3.0 · 8.6

Attack vector

Network

Complexity

Low

Privileges needed

None

User interaction

None

Scope

Changed

Confidentiality

None

Integrity

None

Availability

High

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2019-1840.md and follow it. Check whether this project is affected by CVE-2019-1840. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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