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Cisco IOS XR Software Segment Routing for Intermediate System-to-Intermediate System Denial of Service Vulnerability

cisco-sa-isis-xehpbVNe · High · Published · Updated

A vulnerability in the segment routing feature for the Intermediate System-to-Intermediate System (IS-IS) protocol of Cisco IOS XR 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 of ingress IS-IS packets. An attacker could exploit this vulnerability by sending specific IS-IS packets to an affected device after forming an adjacency. A successful exploit could allow the attacker to cause the IS-IS process on all affected devices that are participating in the Flexible Algorithm to crash and restart, resulting in a 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 must have formed an adjacency. This vulnerability affects segment routing for IS-IS over IPv4 and IPv6 control planes as well as devices that are configured as level 1, level 2, or multi-level routing IS-IS type. Cisco has released software updates that address this vulnerability. There are no 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-xehpbVNe This advisory is part of the September 2024 release of the Cisco IOS XR Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: September 2024 Semiannual Cisco IOS XR Software Security Advisory Bundled Publication.

Cisco advisory ·CSAF JSON

Workarounds

There are no workarounds that address this vulnerability. However, there is a mitigation.

As a best practice, configure IS-IS area authentication so attackers would first have to pass the authentication to trigger this vulnerability. For more information on IS-IS authentication, see Configuring IS-IS Authentication https://www.cisco.com/c/en/us/td/docs/iosxr/ncs5500/routing/24xx/configuration/guide/b-routing-cg-ncs5500-24xx/implementing-isis.html#con_1276647 .

While this mitigation has been deployed and was proven successful in a test environment, customers should determine the applicability and effectiveness in their own environment and under their own use conditions. Customers should be aware that any workaround or mitigation that is implemented may negatively impact the functionality or performance of their network based on intrinsic customer deployment scenarios and limitations. Customers should not deploy any workarounds or mitigations before first evaluating the applicability to their own environment and any impact to such environment.

CVEsCVE-2024-20406
Cisco Bug IDsCSCwi39542
CVSS ScoreBase 7.4
Base 7.4 CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:X/RL:X/RC:X
Product Names From Source
Cisco IOS XR Software, Cisco IOS

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