CVE-2019-12646: Cisco IOS XE

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

A vulnerability in the Network Address Translation (NAT) Session Initiation Protocol (SIP) Application Layer Gateway (ALG) of Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause an affected device to reload. The vulnerability is due to improper processing of transient SIP packets on which NAT is performed on an affected device. An attacker could exploit this vulnerability by using UDP port 5060 to send crafted SIP packets through an affected device that is performing NAT for SIP packets. A successful exploit could allow an attacker to cause the device to reload, resulting in a denial of service (DoS) condition.

Affected products

• Cisco IOS XE: version 15.4(3)s only; version 15.5(3)s only; version 15.6(1)s only; version 16.3.1 only; version 16.4.1 only; version 16.5.1 only; …

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