CVE-2019-12657: Cisco IOS XE

High severity, CVSS 7.5. EPSS: 2% chance of exploitation in the next 30 days.

A vulnerability in Unified Threat Defense (UTD) in Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause an affected device to reload. The vulnerability is due to improper validation of IPv6 packets through the UTD feature. An attacker could exploit this vulnerability by sending IPv6 traffic through an affected device that is configured with UTD. A successful exploit could allow the attacker to cause the device to reload, resulting in a denial of service (DoS) condition.

Affected products

• Cisco IOS XE: version 16.3.6 only

Published 2019-09-25. Last modified 2026-06-17.