CVE-2018-0197

What it is

A vulnerability in the VLAN Trunking Protocol (VTP) subsystem of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, adjacent attacker to corrupt the internal VTP database on an affected device and cause a denial of service (DoS) condition. The vulnerability is due to a logic error in how the affected software handles a subset of VTP packets. An attacker could exploit this vulnerability by sending VTP packets in a sequence that triggers a timeout in the VTP message processing code of the affected software. A successful exploit could allow the attacker to impact the ability to create, modify, or delete VLANs and cause a DoS condition. There are workarounds that address this vulnerability. This vulnerability affects Cisco devices that are running a vulnerable release of Cisco IOS Software or Cisco IOS XE Software, are operating in VTP client mode or VTP server mode, and do not have a VTP domain name configured. The default configuration for Cisco devices that are running Cisco IOS Software or Cisco IOS XE Software and support VTP is to operate in VTP server mode with no domain name configured.

At a glance

Exploitability

Can be exploited from the same network segment without logging in. High risk of service disruption.

Exploit odds

0.6% 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: 0.6% in the next 30 days (EPSS).
• Severity: 6.5 MEDIUM (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

0.6% · EPSS, next 30 days

Weakness

CWE-20 · Improper input validation

Record status

Analyzed

Affected

• Cisco iOS 12.1\(5c\)ex
• Cisco iOS 12.1\(5c\)ex1
• Cisco iOS 12.1\(5c\)ex3
• Cisco iOS 12.1\(6\)ea1
• Cisco iOS 12.1\(6\)ea1a
• Cisco iOS 12.1\(6\)ea2
• Cisco iOS 12.1\(6\)ea2a
• Cisco iOS 12.1\(6\)ea2b

Attack profile CVSS 3.1 · 6.5

Attack vector

Adjacent network

Complexity

Low

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Is it in your code?

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