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.

References

• https://nvd.nist.gov/vuln/detail/CVE-2024-20312
• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-isis-sGjyOUHX