{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-20171",
        "assignerOrgId": "d1c1063e-7a18-46af-9102-31f8928bc633",
        "state": "PUBLISHED",
        "assignerShortName": "cisco",
        "dateReserved": "2025-10-08T11:59:15.391Z",
        "datePublished": "2026-05-20T16:06:38.711Z",
        "dateUpdated": "2026-05-20T18:31:44.204Z"
    },
    "containers": {
        "cna": {
            "title": "Cisco Nexus 3000 and 9000 Series Border Gateway Protocol Denial of Service Vulnerability",
            "metrics": [
                {
                    "format": "cvssV3_1",
                    "cvssV3_1": {
                        "version": "3.1",
                        "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H",
                        "baseScore": 6.8,
                        "baseSeverity": "MEDIUM",
                        "attackVector": "NETWORK",
                        "attackComplexity": "HIGH",
                        "privilegesRequired": "NONE",
                        "userInteraction": "NONE",
                        "scope": "CHANGED",
                        "confidentialityImpact": "NONE",
                        "integrityImpact": "NONE",
                        "availabilityImpact": "HIGH"
                    }
                }
            ],
            "descriptions": [
                {
                    "lang": "en",
                    "value": "A vulnerability in the Border Gateway Protocol (BGP) enforce-first-as feature of Cisco Nexus 3000 Series Switches and Cisco Nexus 9000 Series Switches in standalone NX-OS mode could allow an unauthenticated, remote attacker to trigger BGP peer flaps, resulting in a denial of service (DoS) condition.\r\n\r\nThis vulnerability is due to incorrect parsing of a transitive BGP attribute. An attacker could exploit this vulnerability by sending a crafted BGP update through an established BGP peer session. If the update propagates to an affected device, it could cause the device to drop the BGP session and flap with the BGP peer that is forwarding this update, resulting in a DoS condition."
                }
            ],
            "references": [
                {
                    "url": "https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-bgp-iefab-3hb2pwtx",
                    "name": "cisco-sa-bgp-iefab-3hb2pwtx"
                }
            ],
            "exploits": [
                {
                    "lang": "en",
                    "value": "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": {
                "advisory": "cisco-sa-bgp-iefab-3hb2pwtx",
                "discovery": "INTERNAL",
                "defects": [
                    "CSCwr23951"
                ]
            },
            "problemTypes": [
                {
                    "descriptions": [
                        {
                            "lang": "en",
                            "description": "Always-Incorrect Control Flow Implementation",
                            "type": "cwe",
                            "cweId": "CWE-670"
                        }
                    ]
                }
            ],
            "affected": [
                {
                    "vendor": "Cisco",
                    "product": "Cisco NX-OS Software",
                    "versions": [
                        {
                            "version": "10.2(1)",
                            "status": "affected"
                        },
                        {
                            "version": "10.2(1q)",
                            "status": "affected"
                        },
                        {
                            "version": "10.2(2)",
                            "status": "affected"
                        },
                        {
                            "version": "10.2(3)",
                            "status": "affected"
                        },
                        {
                            "version": "10.2(3t)",
                            "status": "affected"
                        },
                        {
                            "version": "10.2(2a)",
                            "status": "affected"
                        },
                        {
                            "version": "10.3(1)",
                            "status": "affected"
                        },
                        {
                            "version": "10.2(4)",
                            "status": "affected"
                        },
                        {
                            "version": "10.3(2)",
                            "status": "affected"
                        },
                        {
                            "version": "10.3(3)",
                            "status": "affected"
                        },
                        {
                            "version": "10.2(5)",
                            "status": "affected"
                        },
                        {
                            "version": "10.2(3v)",
                            "status": "affected"
                        },
                        {
                            "version": "10.4(1)",
                            "status": "affected"
                        },
                        {
                            "version": "10.3(99w)",
                            "status": "affected"
                        },
                        {
                            "version": "10.2(6)",
                            "status": "affected"
                        },
                        {
                            "version": "10.3(3w)",
                            "status": "affected"
                        },
                        {
                            "version": "10.3(99x)",
                            "status": "affected"
                        },
                        {
                            "version": "10.3(3o)",
                            "status": "affected"
                        },
                        {
                            "version": "10.3(4)",
                            "status": "affected"
                        },
                        {
                            "version": "10.3(3p)",
                            "status": "affected"
                        },
                        {
                            "version": "10.3(4a)",
                            "status": "affected"
                        },
                        {
                            "version": "10.4(2)",
                            "status": "affected"
                        },
                        {
                            "version": "10.3(3q)",
                            "status": "affected"
                        },
                        {
                            "version": "10.3(5)",
                            "status": "affected"
                        },
                        {
                            "version": "10.2(7)",
                            "status": "affected"
                        },
                        {
                            "version": "10.4(3)",
                            "status": "affected"
                        },
                        {
                            "version": "10.3(3x)",
                            "status": "affected"
                        },
                        {
                            "version": "10.3(4g)",
                            "status": "affected"
                        },
                        {
                            "version": "10.5(1)",
                            "status": "affected"
                        },
                        {
                            "version": "10.2(8)",
                            "status": "affected"
                        },
                        {
                            "version": "10.3(3r)",
                            "status": "affected"
                        },
                        {
                            "version": "10.3(6)",
                            "status": "affected"
                        },
                        {
                            "version": "10.4(4)",
                            "status": "affected"
                        },
                        {
                            "version": "10.3(4h)",
                            "status": "affected"
                        },
                        {
                            "version": "10.5(2)",
                            "status": "affected"
                        },
                        {
                            "version": "10.3(7)",
                            "status": "affected"
                        },
                        {
                            "version": "10.4(5)",
                            "status": "affected"
                        },
                        {
                            "version": "10.5(3)",
                            "status": "affected"
                        },
                        {
                            "version": "10.2(9)",
                            "status": "affected"
                        },
                        {
                            "version": "10.4(4g)",
                            "status": "affected"
                        },
                        {
                            "version": "10.6(1)",
                            "status": "affected"
                        },
                        {
                            "version": "10.5(3t)",
                            "status": "affected"
                        },
                        {
                            "version": "10.3(8)",
                            "status": "affected"
                        },
                        {
                            "version": "10.4(6)",
                            "status": "affected"
                        },
                        {
                            "version": "10.5(3s)",
                            "status": "affected"
                        },
                        {
                            "version": "10.5(3e)",
                            "status": "affected"
                        },
                        {
                            "version": "10.5(3o)",
                            "status": "affected"
                        },
                        {
                            "version": "10.6(1s)",
                            "status": "affected"
                        },
                        {
                            "version": "10.5(3p)",
                            "status": "affected"
                        }
                    ],
                    "defaultStatus": "unknown"
                }
            ],
            "providerMetadata": {
                "orgId": "d1c1063e-7a18-46af-9102-31f8928bc633",
                "shortName": "cisco",
                "dateUpdated": "2026-05-20T16:06:38.711Z"
            }
        },
        "adp": [
            {
                "metrics": [
                    {
                        "other": {
                            "type": "ssvc",
                            "content": {
                                "timestamp": "2026-05-20T18:31:37.215391Z",
                                "id": "CVE-2026-20171",
                                "options": [
                                    {
                                        "Exploitation": "none"
                                    },
                                    {
                                        "Automatable": "no"
                                    },
                                    {
                                        "Technical Impact": "partial"
                                    }
                                ],
                                "role": "CISA Coordinator",
                                "version": "2.0.3"
                            }
                        }
                    }
                ],
                "title": "CISA ADP Vulnrichment",
                "providerMetadata": {
                    "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
                    "shortName": "CISA-ADP",
                    "dateUpdated": "2026-05-20T18:31:44.204Z"
                }
            }
        ]
    }
}