{"id":"CVE-2021-1231","aliases":["EUVD-2021-6698","GHSA-hpqm-fqwv-8ffg"],"status":"published","title":"Cisco Nexus 9000 Series Fabric Switches ACI Mode Link Layer Discovery Protocol Port Denial of Service Vulnerability","description":"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. This 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.","severity":{"version":"3.1","score":4.7,"vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.00253,"percentile":0.16897,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-284","CWE-346"],"published":"2021-02-24T19:30:36Z","modified":"2026-06-17T03:31:16Z","products":[{"vendor":"cisco","product":"cisco nx-os system software in aci mode"},{"vendor":"cisco","product":"nx-os"}],"references":[{"url":"https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-apic-lldap-dos-WerV9CFj","tags":["vendor-advisory","x_refsource_CISCO","x_transferred","Vendor Advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2021-1231"},{"url":"https://github.com/advisories/GHSA-hpqm-fqwv-8ffg"}],"sources":{"cve":[{"id":"CVE-2021-1231","title":"Cisco Nexus 9000 Series Fabric Switches ACI Mode Link Layer Discovery Protocol Port Denial of Service Vulnerability","description":"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. This 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.","status":"published","published":"2021-02-24T19:30:36.992Z","modified":"2024-11-08T23:38:56.652Z","cvss":[{"version":"3.1","score":4.7,"vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L","level":"medium","assessor":"cna"}],"cwes":["CWE-284"],"updated_at":"2026-11-02T14:33:08.409321Z"}],"euvd":[{"id":"EUVD-2021-6698","description":"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. This 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.","status":"published","published":"2021-02-24T19:30:36Z","modified":"2024-11-08T23:38:56Z","cvss":[{"version":"3.1","score":4.7,"vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L","level":"medium"}],"updated_at":"2026-11-03T00:05:05.398891Z"}],"ghsa":[{"id":"GHSA-hpqm-fqwv-8ffg","title":"A vulnerability in the Link Layer Discovery Protocol (LLDP) for Nexus 9000 Series Fabric Switches...","description":"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. This 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.","status":"published","published":"2022-05-24T17:42:58Z","modified":"2023-01-29T05:02:59Z","cvss":[{"version":"3.1","score":4.7,"vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L","level":"medium"}],"cwes":["CWE-284","CWE-346"],"updated_at":"2026-11-02T14:45:13.266415Z"}],"nvd":[{"id":"CVE-2021-1231","description":"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. This 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.","status":"published","published":"2021-02-24T20:15:13.193Z","modified":"2026-06-17T03:31:16.75Z","cvss":[{"version":"3.1","score":4.7,"vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L","level":"medium","assessor":"secondary"},{"version":"3.1","score":4.7,"vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L","level":"medium","assessor":"primary"},{"version":"2.0","score":2.9,"vector":"AV:A/AC:M/Au:N/C:N/I:N/A:P","level":"low","assessor":"primary"}],"cwes":["CWE-284","CWE-346"],"updated_at":"2026-11-02T14:06:50.399901Z"}]}}