Cisco Nexus 3000 and 9000 Series Switches Protocol Independent Multicast Version 6 Denial of Service Vulnerability
Summary
-
A vulnerability in the Protocol Independent Multicast Version 6 (PIM6) feature of Cisco Nexus 3000 Series Switches and Cisco Nexus 9000 Series Switches in standalone NX-OS mode could allow an authenticated, low-privileged, remote attacker to trigger a crash of the PIM6 process, resulting in a denial of service (DoS) condition.
This vulnerability is due to improper processing of PIM6 ephemeral data queries. An attacker could exploit this vulnerability by sending a crafted ephemeral query to an affected device through one of the following methods: NX-API REST, NETCONF, RESTConf, gRPC, or Model Driven Telemetry. A successful exploit could allow the attacker to cause the PIM6 process to crash and restart, causing potential adjacency flaps and resulting in a DoS of the PIM6 and ephemeral query processes.
For an example of an ephemeral query, see the About Ephemeral Data in gRPC section of the Cisco Nexus 9000 Series NX-OS Programmability Guide, Release 9.3(x).
Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.
This advisory is available at the following link:
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-nxospc-pim6-vG4jFPh
This advisory is part of the August 2025 Cisco FXOS and NX-OS Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: August 2025 Semiannual Cisco FXOS and NX-OS Software Security Advisory Bundled Publication.
Affected Products
-
At the time of publication, this vulnerability affected Cisco Nexus 3000 Series Switches and Cisco Nexus 9000 Series Switches in standalone NX-OS mode that had the PIM6 feature enabled and at least one of the following features enabled:
- NX-API
- NETCONF
- RESTCONF
- gRPC
- Model Driven Telemetry
Note: The Protocol Independent Multicast Version 4 (PIM4) feature is not affected.
For information about which Cisco software releases are vulnerable, see the Fixed Software section of this advisory.
Determine Whether the PIM6 Feature Is Enabled
To determine whether the PIM6 feature is enabled, use the show feature | include pim6 CLI command, as shown in the following example:
Switch# show feature | include pim6
pim6 1 enabled
Determine Whether a Secondary Feature Is Enabled
To be affected by this vulnerability, a switch must have PIM6 and at least one of the listed features enabled. To determine if any of the listed features are enabled, use the show feature | include featurename command, substituting featurename with the following:
- nxapi
- netconf
- restconf
- grpc
- telemetry
All these features are disabled by default.
Only products listed in the Vulnerable Products section of this advisory are known to be affected by this vulnerability.
Cisco has confirmed that this vulnerability does not affect the following Cisco products:
- Firepower 1000 Series
- Firepower 2100 Series
- Firepower 4100 Series
- Firepower 9300 Security Appliances
- MDS 9000 Series Multilayer Switches
- Nexus 1000 Virtual Edge for VMware vSphere
- Nexus 5500 Platform Switches
- Nexus 5600 Platform Switches
- Nexus 6000 Series Switches
- Nexus 7000 Series Switches
- Nexus 9000 Series Fabric Switches in ACI mode
- Secure Firewall 3100 Series
- Secure Firewall 4200 Series
- UCS 6300 Series Fabric Interconnects
- UCS 6400 Series Fabric Interconnects
- UCS 6500 Series Fabric Interconnects
- UCS X-Series Direct Fabric Interconnect 9108 100G
Workarounds
Fixed Software
-
When considering software upgrades, customers are advised to regularly consult the advisories for Cisco products, which are available from the Cisco Security Advisories page, to determine exposure and a complete upgrade solution.
In all cases, customers should ensure that the devices to be upgraded contain sufficient memory and confirm that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, customers are advised to contact the Cisco Technical Assistance Center (TAC) or their contracted maintenance providers.
Cisco NX-OS Software
To help customers determine their exposure to vulnerabilities in Cisco NX-OS Software, Cisco provides the Cisco Software Checker. This tool identifies any Cisco security advisories that impact a specific software release and the earliest release that fixes the vulnerabilities that are described in each advisory (“First Fixed”). If applicable, the tool also returns the earliest release that fixes all the vulnerabilities described in all the advisories that the Software Checker identifies (“Combined First Fixed”).
To use the tool, go to the Cisco Software Checker page and follow the instructions. Alternatively, use the following form to search for vulnerabilities that affect a specific software release. To use the form, follow these steps:
- Choose which advisories the tool will search-only this advisory, only advisories with a Critical or High Security Impact Rating (SIR), or all advisories.
- Choose the appropriate software.
- Choose the appropriate platform.
- Enter a release number-for example, 10.4(4) for Cisco Nexus 3000 Series Switches or 16.0(8e) for Cisco NX-OS Software in ACI mode.
- Click Check.
Additional Resources
For help determining the best Cisco NX-OS Software release for a Cisco Nexus Switch, see the following Recommended Releases documents. If a security advisory recommends a later release, Cisco recommends following the advisory guidance.
Cisco MDS Series Switches
Cisco Nexus 3000 Series Switches
Cisco Nexus 5500 Platform Switches
Cisco Nexus 5600 Platform Switches
Cisco Nexus 6000 Series Switches
Cisco Nexus 7000 Series Switches
Cisco Nexus 9000 Series Switches
Cisco Nexus 9000 Series ACI-Mode Switches
To determine the best release for Cisco UCS Software, see the Recommended Releases documents in the release notes for the device.
Exploitation and Public Announcements
Source
Cisco Security Vulnerability Policy
-
To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.
Related to This Advisory
URL
Revision History
-
| Version |
Description |
Section |
Status |
Date |
| 1.0 |
Initial public release. |
– |
Final |
2025-AUG-27 |
Show Less
Legal Disclaimer
-
THIS DOCUMENT IS PROVIDED ON AN “AS IS” BASIS AND DOES NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. YOUR USE OF THE INFORMATION ON THE DOCUMENT OR MATERIALS LINKED FROM THE DOCUMENT IS AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS DOCUMENT AT ANY TIME.
A standalone copy or paraphrase of the text of this document that omits the distribution URL is an uncontrolled copy and may lack important information or contain factual errors. The information in this document is intended for end users of Cisco products.
|
