Symptom
A vulnerability in the Link Layer Discovery Protocol (LLDP) for Nexus 9000 Series Fabric Switches in Application Centric Infrastructure (ACI) mode could allow an unauthenticated, adjacent attacker to disable switching on a small form-factor pluggable (SFP) interface.
The vulnerability is due to incomplete validation of the source of a received LLDP packet. An attacker could exploit this vulnerability by sending a crafted LLDP packet on an SFP interface to an affected device. A successful exploit could allow the attacker to disable switching on the SFP interface, which could disrupt network traffic.
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://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-apic-lldap-dos-WerV9CFj
Conditions
Please refer to the Security Advisory.
Workaround
Please refer to the Security Advisory.
Further Problem Description
Please refer to the Security Advisory.
*PSIRT Evaluation:*
The Cisco PSIRT has assigned this bug the following CVSS version 3 score. The Base CVSS score as of the time of evaluation is 4.7:
https://tools.cisco.com/security/center/cvssCalculator.x?vector=CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L
CVE ID CVE-2021-1231 has been assigned to document this issue.
Additional information on Cisco's security vulnerability policy can be found at the following URL:
https://tools.cisco.com/security/center/resources/security_vulnerability_policy.html
