Summary

• A vulnerability in the Link Layer Discovery Protocol (LLDP) feature of Cisco NX-OS Software could allow an unauthenticated, adjacent attacker to cause the LLDP process to restart, which could cause an affected device to reload unexpectedly.

  This vulnerability is due to improper handling of specific fields in an LLDP frame. An attacker could exploit this vulnerability by sending a crafted LLDP packet to an interface of an affected device. A successful exploit could allow the attacker to cause the device to reload, resulting in a denial of service (DoS) condition.

  Note: LLDP is a Layer 2 link protocol. To exploit this vulnerability, an attacker would need to be directly connected to an interface of an affected device, either physically or logically (for example, through a Layer 2 Tunnel configured to transport the LLDP protocol).

  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-n3kn9k_aci_lldp_dos-NdgRrrA3

  This advisory is part of the February 2026 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 2026 Semiannual Cisco FXOS and NX-OS Software Security Advisory Bundled Publication.

Affected Products

• Vulnerable Products

  This vulnerability affects the following Cisco products if they are running a vulnerable software release and have the LLDP feature enabled globally and on at least one interface:

  • Nexus 3000 Series Switches (CSCwi75282)
  • Nexus 9000 Series Fabric Switches in ACI mode (CSCwq33193)
  • Nexus 9000 Series Switches in standalone NX-OS mode (CSCwi75282)
  • UCS X-Series Direct Fabric Interconnects 9108 100G (CSCwq60777)

  For information about which Cisco software releases are vulnerable, see the Fixed Software section of this advisory.

  Determine the Status of LLDP on Cisco NX-OS Software in Standalone Mode

  The LLDP feature is disabled by default on Cisco Nexus Switches that are running Cisco NX-OS Software in standalone mode. To determine if the LLDP feature has been enabled, use the show feature | include lldp command at the device CLI. The following example shows that the LLDP feature is enabled:

  switch# show feature | include lldp
  lldp                   1          enabled 

  If the LLDP feature has been enabled, LLDP is also enabled on all interfaces by default. The processing of incoming LLDP packets can be selectively disabled on a specific interface by using the no lldp receive interface-level configuration command.

  To determine the status of LLDP on a specific interface, use the show lldp interface ethernet module/interface command at the device CLI. If the enable (rx) status is set to Y, the interface accepts incoming LLDP packets, as shown in the following example:

  switch# show lldp interface ethernet 1/1
  Interface Information:
    Enable (tx/rx/dcbx): Y/Y/Y    Port Mac address: 00:a6:ca:b6:84:5a

  Determine the Status of LLDP on Cisco Nexus 9000 Series Fabric Switches in ACI Mode

  The LLDP feature is enabled by default on Cisco Nexus 9000 Series Fabric Switches in ACI mode and cannot be fully disabled. LLDP is enabled by default on all fabric ports and access ports.

  The processing of incoming LLDP packets can be selectively disabled on a specific access port by using the no lldp receive interface-level configuration command from the APIC NX-OS style CLI, or by having LLDP disabled in the applied access policy. For more information, see the Access Policies Overview section of the Cisco Application Centric Infrastructure Fundamentals Guide.

  To determine the status of LLDP on a specific interface, use the show lldp interface ethernet module/interface command at the device CLI. If the enable (rx) status is set to Y, the interface accepts incoming LLDP packets, as shown in the following example:

  switch# show lldp interface ethernet 1/1
  Interface Information:
    Enable (tx/rx/dcbx): Y/Y/N    Port Mac address: 50:87:89:a2:10:39

  Determine the Status of LLDP on Cisco UCS X-Series Direct Fabric Interconnects 9108 100G

  The LLDP feature is enabled by default on Cisco UCS X-Series Direct Fabric Interconnect 9108 100G and cannot be fully disabled. LLDP is always enabled on the following interfaces:

  • Ethernet uplink ports (network interfaces that connect to upstream switches for network connectivity)
  • Ethernet port channel members
  • Fibre Channel over Ethernet (FCoE) uplink ports
  • Management interface (mgmt0)

  LLDP may also be enabled on server ports (interfaces that are presented to the servers in the Cisco UCS Manager domain) and appliance ports (interfaces that connect to directly attached NFS storage) through a network control policy. For more information, see the Configuring Network Control Policies section of the Cisco UCS Manager Network Management Guide.

  To determine the status of LLDP on a specific interface, use the connect nxos command at the device CLI, then use the show lldp interface ethernet module/interface command. If the enable (rx) status is set to Y, the interface accepts incoming LLDP packets, as shown in the following example:

  FI-A# show lldp interface ethernet 1/1
  Interface Information:
   Enable (tx/rx/dcbx):Y/Y/Y    Port Mac address: 00:c8:8b:84:a2:54

  
  

  Products Confirmed Not Vulnerable

  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 5500 Platform Switches
  • Nexus 5600 Platform Switches
  • Nexus 6000 Series Switches
  • Nexus 7000 Series Switches
  • Secure Firewall 3100 Series
  • Secure Firewall 4200 Series
  • UCS 6300 Series Fabric Interconnects
  • UCS 6400 Series Fabric Interconnects

Workarounds

• There are no workarounds that address this vulnerability.

Fixed Software

• Cisco considers any workarounds and mitigations (if applicable) to be temporary solutions until an upgrade to a fixed software release is available. To fully remediate this vulnerability and avoid future exposure as described in this advisory, Cisco strongly recommends that customers upgrade to the fixed software indicated in this advisory.

  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:

  1. Choose which advisories the tool will search-only this advisory, only advisories with a Critical or High Security Impact Rating (SIR), or all advisories.
  2. Choose the appropriate software.
  3. Choose the appropriate platform.
  4. 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.
  5. Click Check.

  
  

  Only this advisory All Critical and High advisories All advisories Cisco NX-OS Software Cisco NX-OS Software in ACI Mode Any Platform MDS 9000 Series Multilayer Switches Nexus 3000 Series Switches Nexus 5000 Series Switches Nexus 6000 Series Switches Nexus 7000 Series Switches Nexus 9000 Series Switches

  
  

  Cisco UCS Software

  In the following table, the left column lists Cisco software releases. The center column indicates whether a release is affected by the vulnerability described in this advisory and the first vulnerable release. The right column indicates the first release that includes the fix for this vulnerability.

  UCS 9108 100G Fabric Interconnects

  Cisco UCS Software Release	First Fixed Release for UCS Manager Mode	First Fixed Release for Intersight Managed Mode
  4.3	4.3(6e)	4.3(6.260003)
  6.0	Not vulnerable	Not vulnerable

  The Cisco Product Security Incident Response Team (PSIRT) validates only the affected and fixed release information that is documented in this advisory.

  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

• The Cisco Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory.

Source

• This vulnerability was found during the resolution of a Cisco Technical Assistance Center (TAC) support case.

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-n3kn9k_aci_lldp_dos-NdgRrrA3

Revision History

• Version	Description	Section	Status	Date
  1.0	Initial public release.	-	Final	2026-FEB-25

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