CVE-2018-0197: Cisco IOS

Medium severity, CVSS 6.5. EPSS: 0.6% chance of exploitation in the next 30 days.

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.

Affected products

• Cisco IOS: version 12.1(5c)ex only; version 12.1(5c)ex1 only; version 12.1(5c)ex3 only; version 12.1(6)ea1 only; version 12.1(6)ea1a only; version 12.1(6)ea2 only; …
• Cisco IOS XE: affected versions not specified; version 3.2.0ja only; version 3.2.0se only; version 3.2.0sg only; version 3.2.1se only; version 3.2.1sg only; …

Published 2018-10-05. Last modified 2026-06-17.