Is CVE-2026-20301 being actively exploited?

CVE-2026-20301 is not currently listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

What is the CVSS score for CVE-2026-20301?

CVE-2026-20301 has a CVSS 3.1 base score of 8.6 (HIGH).

CVE-2026-20301

HIGH · CVSS 8.6EPSS 0.6%EU EUVD

A vulnerability in the Extensible Messaging Client Protocol (XMCP), also referred to as the External Client protocol, of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to improper handling of malformed XMCP packets. An attacker could exploit this vulnerability by sending a malformed XMCP packet to an affected device. A successful exploit could allow the attacker to cause the affected device to reload unexpectedly, resulting in a DoS condition. The attacker does not need the XMCP client username to exploit this vulnerability.

Key facts

CVSS score: 8.6 (v3.1)
Severity: HIGH
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Weakness (CWE): CWE-606
EPSS score: 0.6% (46th percentile)
In CISA KEV: No
In EU EUVD: Yes (EUVD-2026-53467)
Published: August 5, 2026
NVD last modified: September 17, 2026
Status: Analyzed

EU Vulnerability Database (EUVD)

This vulnerability is also tracked by ENISA as EUVD-2026-53467 in the EU Vulnerability Database. Last updated in EUVD on August 5, 2026.

View on the EU Vulnerability Database

Affected products

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and 377 more…

Certified products that may be affected

11 FIPS 140 or Common Criteria certified products, from automated matching by sec-certs.org.

Cisco Embedded Services 9300 and 3300 Series Switches (ESS9300 & ESS3300) running IOS-XE 17.15 - Cisco Systems, Inc. - Common Criteria CCEVS-VR-VID-11662-2026 - active
Cisco Catalyst 8000V Edge (C8000V) running IOS-XE 17.15 - Cisco Systems, Inc. - Common Criteria Certificate Number: 2025/161 - active
Cisco 1000 Series Integrated Services Routers (C1100), Cisco Catalyst IR1800 Rugged Series Routers (IR1800), Cisco Catalyst IR8300 Rugged Series Routers (IR8300) running IOS-XE 17.15 - Cisco Systems, Inc. - Common Criteria CCEVS-VR-VID-11643-2025 - active
Cisco Catalyst Industrial Ethernet 9300 Rugged Series Switches running IOS-XE 17.15 - Cisco Systems, Inc. - Common Criteria CCEVS-VR-VID-11603-2025 - active
Cisco Aggregation Services Router 1000 Series (ASR1K), Cisco Catalyst 8200, 8300, 8500 Series Edge Routers (Cat8K) running IOS-XE version 17.15 - Cisco Systems, Inc. - Common Criteria CCEVS-VR-VID-11642-2025 - active

See all 11 in the Security Certifications Explorer.

References

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ios-xmcp-thbAr34t(Mitigation, Vendor Advisory)

Last updated September 19, 2026 · Source: NVD, CISA KEV, FIRST.org EPSS

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