A vulnerability in the Intermediate System-to-Intermediate System (IS-IS) feature of Cisco NX-OS Software for Cisco Nexus 3000 Series Switches and Cisco Nexus 9000 Series Switches in standalone NX-OS mode could allow an unauthenticated, adjacent attacker to cause the IS-IS process to unexpectedly restart, which could cause an affected device to reload. This vulnerability is due to insufficient input validation when parsing an ingress IS-IS packet. An attacker could exploit this vulnerability by sending a crafted IS-IS packet to an affected device. A successful exploit could allow the attacker to cause the unexpected restart of the IS-IS process, which could cause the affected device to reload, resulting in 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.

Metrics

No CVSS v4.0

Attack Vector Adjacent Network

Attack Complexity Low

Privileges Required None

Scope Changed

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploitation none

Automatable no

Technical Impact partial

Affected Vendors & Products

Vendors Products
Cisco
  • Nexus
  • Nexus 3000
  • Nexus 9000
  • Nx-os

No data.

No data.

References
Link Providers
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-n39k-isis-dos-JhJA8Rfx cve-icon cve-icon
History

Wed, 27 Aug 2025 22:00:00 +0000

Type Values Removed Values Added
First Time appeared Cisco
Cisco nexus
Cisco nexus 3000
Cisco nexus 9000
Cisco nx-os
Vendors & Products Cisco
Cisco nexus
Cisco nexus 3000
Cisco nexus 9000
Cisco nx-os

Wed, 27 Aug 2025 19:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Wed, 27 Aug 2025 16:45:00 +0000

Type Values Removed Values Added
Description A vulnerability in the Intermediate System-to-Intermediate System (IS-IS) feature of Cisco NX-OS Software for Cisco Nexus 3000 Series Switches and Cisco Nexus 9000 Series Switches in standalone NX-OS mode could allow an unauthenticated, adjacent attacker to cause the IS-IS process to unexpectedly restart, which could cause an affected device to reload. This vulnerability is due to insufficient input validation when parsing an ingress IS-IS packet. An attacker could exploit this vulnerability by sending a crafted IS-IS packet to an affected device. A successful exploit could allow the attacker to cause the unexpected restart of the IS-IS process, which could cause the affected device to reload, resulting in 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.
Title Cisco Nexus 3000 and 9000 Series Switches IS-IS Protocol <TBD> Denial of Service Vulnerability
Weaknesses CWE-733
References
Metrics cvssV3_1

{'score': 7.4, 'vector': 'CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H'}
cve-icon MITRE

Status: PUBLISHED

Assigner: cisco

Published:

Updated: 2025-08-27T18:18:32.250Z

Reserved: 2024-10-10T19:15:13.238Z

Link: CVE-2025-20241

cve-icon Vulnrichment

Updated: 2025-08-27T18:18:26.109Z

cve-icon NVD

Status : Received

Published: 2025-08-27T17:15:34.650

Modified: 2025-08-27T17:15:34.650

Link: CVE-2025-20241

cve-icon Redhat

No data.