{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "state": "PUBLISHED",
        "cveId": "CVE-2021-27854",
        "assignerOrgId": "37e5125f-f79b-445b-8fad-9564f167944b",
        "assignerShortName": "certcc",
        "datePublished": "2022-09-27T18:40:12.738Z",
        "dateUpdated": "2025-11-04T19:12:26.598Z",
        "dateReserved": "2021-03-01T00:00:00.000Z"
    },
    "containers": {
        "cna": {
            "title": "L2 network filtering bypass using stacked VLAN0, LLC/SNAP headers, and Ethernet to Wifi frame translation",
            "datePublic": "2022-09-27T00:00:00.000Z",
            "providerMetadata": {
                "orgId": "37e5125f-f79b-445b-8fad-9564f167944b",
                "shortName": "certcc",
                "dateUpdated": "2022-10-12T00:00:00.000Z"
            },
            "descriptions": [
                {
                    "lang": "en",
                    "value": "Layer 2 network filtering capabilities such as IPv6 RA guard can be bypassed using combinations of VLAN 0 headers, LLC/SNAP headers, and converting frames from Ethernet to Wifi and its reverse."
                }
            ],
            "affected": [
                {
                    "vendor": "IETF",
                    "product": "P802.1Q",
                    "versions": [
                        {
                            "version": "D1.0",
                            "status": "affected",
                            "lessThanOrEqual": "D1.0",
                            "versionType": "custom"
                        }
                    ]
                },
                {
                    "vendor": "IETF",
                    "product": "draft-ietf-v6ops-ra-guard",
                    "versions": [
                        {
                            "version": "08",
                            "status": "affected",
                            "lessThanOrEqual": "08",
                            "versionType": "custom"
                        }
                    ]
                },
                {
                    "vendor": "IEEE",
                    "product": "802.2",
                    "versions": [
                        {
                            "version": "802.2h-1997",
                            "status": "affected",
                            "lessThanOrEqual": "802.2h-1997",
                            "versionType": "custom"
                        }
                    ]
                }
            ],
            "references": [
                {
                    "url": "https://datatracker.ietf.org/doc/draft-ietf-v6ops-ra-guard/08/"
                },
                {
                    "url": "https://standards.ieee.org/ieee/802.2/1048/"
                },
                {
                    "url": "https://standards.ieee.org/ieee/802.1Q/10323/"
                },
                {
                    "url": "https://kb.cert.org/vuls/id/855201"
                },
                {
                    "url": "https://blog.champtar.fr/VLAN0_LLC_SNAP/"
                }
            ],
            "credits": [
                {
                    "lang": "en",
                    "value": "Etienne Champetier (@champtar) <champetier.etienne@gmail.com>"
                }
            ],
            "problemTypes": [
                {
                    "descriptions": [
                        {
                            "type": "CWE",
                            "lang": "en",
                            "description": "CWE-290: Authentication Bypass by Spoofing",
                            "cweId": "CWE-290"
                        }
                    ]
                }
            ],
            "source": {
                "discovery": "EXTERNAL"
            }
        },
        "adp": [
            {
                "title": "CVE Program Container",
                "references": [
                    {
                        "url": "https://datatracker.ietf.org/doc/draft-ietf-v6ops-ra-guard/08/",
                        "tags": [
                            "x_transferred"
                        ]
                    },
                    {
                        "url": "https://standards.ieee.org/ieee/802.2/1048/",
                        "tags": [
                            "x_transferred"
                        ]
                    },
                    {
                        "url": "https://standards.ieee.org/ieee/802.1Q/10323/",
                        "tags": [
                            "x_transferred"
                        ]
                    },
                    {
                        "url": "https://kb.cert.org/vuls/id/855201",
                        "tags": [
                            "x_transferred"
                        ]
                    },
                    {
                        "url": "https://blog.champtar.fr/VLAN0_LLC_SNAP/",
                        "tags": [
                            "x_transferred"
                        ]
                    },
                    {
                        "url": "https://www.kb.cert.org/vuls/id/855201"
                    }
                ],
                "providerMetadata": {
                    "orgId": "af854a3a-2127-422b-91ae-364da2661108",
                    "shortName": "CVE",
                    "dateUpdated": "2025-11-04T19:12:26.598Z"
                }
            },
            {
                "metrics": [
                    {
                        "cvssV3_1": {
                            "scope": "CHANGED",
                            "version": "3.1",
                            "baseScore": 4.7,
                            "attackVector": "ADJACENT_NETWORK",
                            "baseSeverity": "MEDIUM",
                            "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N",
                            "integrityImpact": "LOW",
                            "userInteraction": "NONE",
                            "attackComplexity": "LOW",
                            "availabilityImpact": "NONE",
                            "privilegesRequired": "NONE",
                            "confidentialityImpact": "NONE"
                        }
                    },
                    {
                        "other": {
                            "type": "ssvc",
                            "content": {
                                "timestamp": "2025-05-21T15:06:23.882465Z",
                                "id": "CVE-2021-27854",
                                "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": "2025-05-21T15:06:44.230Z"
                }
            }
        ]
    }
}