Is CVE-2026-20074 in the CISA KEV catalog?

No. CVE-2026-20074 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-20074?

CVE-2026-20074 has a CVSS v3 base score of 7.4 (HIGH).

What is the EPSS score for CVE-2026-20074?

CVE-2026-20074 has an EPSS score of 0.16% (6th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix or mitigate CVE-2026-20074?

No published fix for CVE-2026-20074 has been found yet. Check the linked vendor advisories for guidance as it becomes available.

CVE & CISA-KEV Catalog

CVE-2026-20074

HIGH

7.4

CVSS v3

NVD

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.

CWE-1287Improper Validation of Specified Type of Input

How to fix

No published remediation has been found for this vulnerability's affected products yet.

Mitigation guidance may be in the linked vendor advisories in the References section below.

CVSS v3 Vector

Exploitability

Attack VectorAdjacent

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeChanged

Impact

ConfidentialityNone

IntegrityNone

AvailabilityHigh

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

Exploit Intelligence

0.16%probability of exploitation in 30 days

6thpercentile

Low risk: more likely to be exploited than 6% of all known CVEs.

References

Other references1

sec.cloudapps.cisco.com

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-03-12.