Cisco IOS and IOS XE Software Intermediate System-to-Intermediate System Denial of Service Vulnerability

A vulnerability in the Intermediate System-to-Intermediate System (IS-IS) protocol of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, adjacent attacker to cause a denial of service (DoS) condition on an affected device.

This vulnerability is due to insufficient input validation when parsing an ingress IS-IS packet. An attacker could exploit this vulnerability by sending a crafted IS-IS packet to an affected device after forming an adjacency. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a denial of service (DoS) condition.

Note: The IS-IS protocol is a routing protocol. To exploit this vulnerability, an attacker must be Layer 2-adjacent to the affected device and have formed an adjacency.

Cisco has released software updates that address this vulnerability. There are workarounds that address this vulnerability.

This advisory is available at the following link:
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-isis-sGjyOUHX [“https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-isis-sGjyOUHX”]

This advisory is part of the March 2024 release of the Cisco IOS and IOS XE Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: March 2024 Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled Publication [“https://sec.cloudapps.cisco.com/security/center/viewErp.x?alertId=ERP-75056”].