CVE-2026-20074 | IOS XR Software - IS-IS Operational Intel

Executive Risk Summary

"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, resulting in a temporary loss of connectivity to advertised networks and a denial of service (DoS) condition. This vulnerability is due to insufficient input validation of ingress IS-IS packets."

Operational Audit Arsenal

Target Type Firmware

Target Asset IOS XR Software

Standard Path Router Firmware

Manual Verification Required

This is a non-Windows asset (Cisco). Use the target asset details and official path provided above to verify your current version against the official vendor advisories listed below.

Patch Impact Forecast

Reboot Required Likely

Temporary loss of connectivity to advertised networks

Internal Work Notes

CVE-2026-20074: IS-IS DoS vulnerability in Cisco IOS XR Software, requires adjacent attacker and formed adjacency to exploit, resulting in temporary loss of connectivity and DoS condition.

Technical Intelligence & Operational Utilities • Delivered Weekly

Intelligence Sources

Official Advisoryhttps://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-isis-dos-kDMxpSzK

Related Cisco Threats

CVE-2026-20079 CVSS 10

Secure Firewall Management Center (FMC) Software

CVE-2026-20127 CVSS 10

Catalyst SD-WAN Controller - Peering Authentication

CVE-2025-20188 CVSS 10

Cisco IOS XE - Wireless LAN Controllers

Data compiled from NVD, MSRC, and CISA KEV Catalog. Intelligence synthesized via AI. Scripts provided for diagnostic purposes under MIT License.