CVE-2018-0421

What it is

A vulnerability in TCP connection management in Cisco Prime Access Registrar could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition when the application unexpectedly restarts. The vulnerability is due to incorrect handling of incoming TCP SYN packets to specific listening ports. The improper handling of the TCP SYN packets could cause a system file description to be allocated and not freed. An attacker could exploit this vulnerability by sending a crafted stream of TCP SYN packets to the application. A successful exploit could allow the attacker to cause the application to eventually restart if a file description cannot be obtained.

At a glance

Exploitability

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

Exploit odds

3.5% chance of exploitation in the next 30 days (EPSS).

Fix

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

Timeline

1. 2018-10-05 14:29 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 01:30 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 3.5% in the next 30 days (EPSS).
• Severity: 8.6 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2018-10-05 14:29 UTC

Last modified

2026-06-17 01:30 UTC

Exploit probability

3.5% · EPSS, next 30 days

Weakness

CWE-399

Record status

Modified

Affected

• Cisco Prime Access Registrar < 7.3.0.4
• Cisco Prime Access Registrar < 8.0.1.1
• Cisco Prime Access Registrar Jumpstart < 7.3.0.4
• Cisco Prime Access Registrar Jumpstart < 8.0.1.1

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-2018-0421.md and follow it. Check whether this project is affected by CVE-2018-0421. 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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