CVE-2026-20074
high
Cisco CVSS v3 Base Score
7.4
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
EPSS Score
0.0%
Exploitation probability in 30 days
Top 95% most likely to be exploited
Attack Characteristics
Attack Vector
Adjacent
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Confidentiality
None
Integrity
None
Availability
High
Vulnerability Report
Generated by CyberWatcher
Description
A vulnerability in the Intermediate System-to-Intermediate System (IS-IS) multi-instance routing feature of Cisco IOS XR Software could allow an unauthenticated, adjacent attacker to cause the IS-IS process to restart unexpectedly.
This vulnerability is due to insufficient input validation of ingress IS-IS packets. An attacker could exploit this vulnerability by sending crafted IS-IS packets to an affected device after forming an adjacency. A successful exploit could allow the attacker to cause the IS-IS process to restart unexpectedly, resulting in a temporary loss of connectivity to advertised networks and 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 must have formed an adjacency.