Cisco NX-OS Software MPLS Encapsulated IPv6 Denial of Service Vulnerability

A vulnerability with the handling of MPLS traffic for Cisco NX-OS Software could allow an unauthenticated, remote attacker to cause the netstack process to unexpectedly restart, which could cause the device to stop processing network traffic or to reload.

This vulnerability is due to lack of proper error checking when processing an ingress MPLS frame. An attacker could exploit this vulnerability by sending a crafted IPv6 packet that is encapsulated within an MPLS frame to an MPLS-enabled interface of the targeted device. A successful exploit could allow the attacker to cause a denial of service (DoS) condition.

Note: The IPv6 packet can be generated multiple hops away from the targeted device and then encapsulated within MPLS. The DoS condition may occur when the NX-OS device processes the packet.

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-ipv6-mpls-dos-R9ycXkwM [“https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ipv6-mpls-dos-R9ycXkwM”]

This advisory is part of the February 2024 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: February 2024 Semiannual Cisco FXOS and NX-OS Software Security Advisory Bundled Publication [“https://sec.cloudapps.cisco.com/security/center/viewErp.x?alertId=ERP-75059”].