CVE-2026-20301

Vulnerability overview

A vulnerability in the Extensible Messaging Client Protocol (XMCP), also referred to as the External Client protocol, of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to improper handling of malformed XMCP packets. An attacker could exploit this vulnerability by sending a malformed XMCP packet to an affected device. A successful exploit could allow the attacker to cause the affected device to reload unexpectedly, resulting in a DoS condition. The attac...

Affected product and versions

Product

Cisco Cisco IOS XE Software, IOS

Affected versions

>= 17.2.1a, >= 16.12.1y, >= 16.12.3s, >= 16.7.1b, >= 16.6.2, >= 16.6.5, >= 16.12.1w, >= 16.9.1d, >= 17.3.1, >= 16.9.4c, >= 16.7.1, >= 17.2.1, >= 16.6.8, >= 16.9.1b, >= 16.9.2s, >= 16.12.4, >= 16.12.3a, >= 17.1.1s, >= 16.11.1a, >= 16.7.2

Fixed versions

No verified fixed-version field is available yet

Technical data

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

CWE

CWE-606