CVE-2025-20241
Cisco Nexus 3000 and 9000 Series Switches IS-IS Protocol <TBD> Denial of Service Vulnerability
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.
Weakness: CWE-733
Affected products
| Vendor | Product | Category | Matched by |
|---|---|---|---|
| Cisco | Cisco NX-OS Software | Routing & Switching | cna-assigner |
Vendor-reported products (1)
- Cisco · Cisco NX-OS Software
Vendor advisory
cisco-sa-n39k-isis-dos-JhJA8Rfx
Cisco Nexus 3000 and 9000 Series Switches Intermediate System-to-Intermediate System Denial of Service Vulnerability
Cisco’s rating: High (advisory CVSS 7.4) · Published Aug 27, 2025
Bug ID: CSCwn49153
The vendor’s rating applies to the whole advisory and can differ from this CVE’s own CVSS severity. Where this comes from