Vulnerability-Lookup

CVE-2021-27862 (GCVE-0-2021-27862)

Vulnerability from cvelistv5 – Published: 2022-09-27 18:40 – Updated: 2025-11-04 19:12

Title

L2 network filtering bypass using stacked VLAN0 and LLC/SNAP headers with an invalid length during Ethernet to Wifi frame translation

Summary

Layer 2 network filtering capabilities such as IPv6 RA guard can be bypassed using LLC/SNAP headers with invalid length and Ethernet to Wifi frame conversion (and optionally VLAN0 headers).

Severity

4.7 (Medium)


                        
                          CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2025-05-21 15:04 UTC

CWE

CWE-130 - Improper Handling of Length Parameter
CWE-290 - Authentication Bypass by Spoofing

Assigner

certcc mitre root

References

5 references

URL	Tags
https://datatracker.ietf.org/doc/draft-ietf-v6ops…
https://standards.ieee.org/ieee/802.2/1048/
https://kb.cert.org/vuls/id/855201
https://blog.champtar.fr/VLAN0_LLC_SNAP/
https://www.kb.cert.org/vuls/id/855201

Impacted products

2 products

Vendor	Product	Version	CPE status
IEEE	802.2	Affected: 802.2h-1997 , ≤ 802.2h-1997 (custom)	guessed
IETF	draft-ietf-v6ops-ra-guard-08	Affected: 08 , ≤ 08 (custom)	guessed

Date Public

2022-09-27 00:00

Credits

Etienne Champetier (@champtar) <champetier.etienne@gmail.com>

Show details on NVD website

JSON

To clipboard

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              "url": "https://datatracker.ietf.org/doc/draft-ietf-v6ops-ra-guard/08/"
            },
            {
              "url": "https://standards.ieee.org/ieee/802.2/1048/"
            },
            {
              "url": "https://kb.cert.org/vuls/id/855201"
            },
            {
              "url": "https://blog.champtar.fr/VLAN0_LLC_SNAP/"
            }
          ],
          "source": {
            "discovery": "EXTERNAL"
          },
          "title": "L2 network filtering bypass using stacked VLAN0 and LLC/SNAP headers with an invalid length during Ethernet to Wifi frame translation"
        }
      },
      "cveMetadata": {
        "assignerOrgId": "37e5125f-f79b-445b-8fad-9564f167944b",
        "assignerShortName": "certcc",
        "cveId": "CVE-2021-27862",
        "datePublished": "2022-09-27T18:40:14.712Z",
        "dateReserved": "2021-03-01T00:00:00.000Z",
        "dateUpdated": "2025-11-04T19:12:28.789Z",
        "state": "PUBLISHED"
      },
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}

CISCO-SA-VU855201-J3Z8CKTX

Vulnerability from csaf_cisco - Published: 2022-09-27 16:00 - Updated: 2022-10-05 18:16

Summary

Vulnerabilities in Layer 2 Network Security Controls Affecting Cisco Products: September 2022

Scope

4 vulnerabilities in this advisory, including CVE-2021-27862.

CVE-2021-27862

Open the full advisory

FKIE_CVE-2021-27862

Vulnerability from fkie_nvd - Published: 2022-09-27 19:15 - Updated: 2026-06-17 03:45

Severity

4.7 (Medium) - CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
4.7 (Medium) - CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N

Summary

Layer 2 network filtering capabilities such as IPv6 RA guard can be bypassed using LLC/SNAP headers with invalid length and Ethernet to Wifi frame conversion (and optionally VLAN0 headers).

References

URL	Tags
cret@cert.org	https://blog.champtar.fr/VLAN0_LLC_SNAP/
cret@cert.org	https://datatracker.ietf.org/doc/draft-ietf-v6ops-ra-guard/08/	Vendor Advisory
cret@cert.org	https://kb.cert.org/vuls/id/855201
cret@cert.org	https://standards.ieee.org/ieee/802.2/1048/	Vendor Advisory
af854a3a-2127-422b-91ae-364da2661108	https://blog.champtar.fr/VLAN0_LLC_SNAP/
af854a3a-2127-422b-91ae-364da2661108	https://datatracker.ietf.org/doc/draft-ietf-v6ops-ra-guard/08/	Vendor Advisory
af854a3a-2127-422b-91ae-364da2661108	https://kb.cert.org/vuls/id/855201
af854a3a-2127-422b-91ae-364da2661108	https://standards.ieee.org/ieee/802.2/1048/	Vendor Advisory
af854a3a-2127-422b-91ae-364da2661108	https://www.kb.cert.org/vuls/id/855201

Impacted products

	Vendor	Product	Version
	ieee	ieee_802.2	*
	ietf	p802.1q	*

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "802.2",
          "vendor": "IEEE",
          "versions": [
            {
              "lessThanOrEqual": "802.2h-1997",
              "status": "affected",
              "version": "802.2h-1997",
              "versionType": "custom"
            }
          ]
        },
        {
          "product": "draft-ietf-v6ops-ra-guard-08",
          "vendor": "IETF",
          "versions": [
            {
              "lessThanOrEqual": "08",
              "status": "affected",
              "version": "08",
              "versionType": "custom"
            }
          ]
        }
      ],
      "source": "cret@cert.org"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:ieee:ieee_802.2:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "D5B0DDC2-21C5-4682-9AA2-055BF7C722DA",
              "versionEndIncluding": "802.2h-1997",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    },
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:ietf:p802.1q:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "94105D2E-950F-4290-8840-301FA908BC8C",
              "versionEndIncluding": "d1.0",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Layer 2 network filtering capabilities such as IPv6 RA guard can be bypassed using LLC/SNAP headers with invalid length and Ethernet to Wifi frame conversion (and optionally VLAN0 headers)."
    },
    {
      "lang": "es",
      "value": "Las capacidades de filtrado de red de capa 2, como la protecci\u00f3n RA de IPv6, pueden omitirse usando encabezados LLC/SNAP con una longitud no v\u00e1lida y la conversi\u00f3n de tramas de Ethernet a Wifi (y, opcionalmente, encabezados VLAN0)"
    }
  ],
  "id": "CVE-2021-27862",
  "lastModified": "2026-06-17T03:45:32.623",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "ADJACENT_NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 4.7,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "LOW",
          "privilegesRequired": "NONE",
          "scope": "CHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 1.4,
        "source": "nvd@nist.gov",
        "type": "Primary"
      },
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "ADJACENT_NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 4.7,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "LOW",
          "privilegesRequired": "NONE",
          "scope": "CHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 1.4,
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2021-27862",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2025-05-21T15:04:33.466068Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2022-09-27T19:15:09.403",
  "references": [
    {
      "source": "cret@cert.org",
      "url": "https://blog.champtar.fr/VLAN0_LLC_SNAP/"
    },
    {
      "source": "cret@cert.org",
      "tags": [
        "Vendor Advisory"
      ],
      "url": "https://datatracker.ietf.org/doc/draft-ietf-v6ops-ra-guard/08/"
    },
    {
      "source": "cret@cert.org",
      "url": "https://kb.cert.org/vuls/id/855201"
    },
    {
      "source": "cret@cert.org",
      "tags": [
        "Vendor Advisory"
      ],
      "url": "https://standards.ieee.org/ieee/802.2/1048/"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "url": "https://blog.champtar.fr/VLAN0_LLC_SNAP/"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Vendor Advisory"
      ],
      "url": "https://datatracker.ietf.org/doc/draft-ietf-v6ops-ra-guard/08/"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "url": "https://kb.cert.org/vuls/id/855201"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Vendor Advisory"
      ],
      "url": "https://standards.ieee.org/ieee/802.2/1048/"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "url": "https://www.kb.cert.org/vuls/id/855201"
    }
  ],
  "sourceIdentifier": "cret@cert.org",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-130"
        },
        {
          "lang": "en",
          "value": "CWE-290"
        }
      ],
      "source": "cret@cert.org",
      "type": "Secondary"
    },
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-290"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}

GHSA-4FHF-8PH3-PP6C

Vulnerability from github – Published: 2022-09-28 00:00 – Updated: 2025-11-04 21:30

Details

Layer 2 network filtering capabilities such as IPv6 RA guard can be bypassed using LLC/SNAP headers with invalid length and Ethernet to Wifi frame conversion (and optionally VLAN0 headers).

Severity

4.7 (Medium)


                  
                    CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N

Show details on source website

JSON

To clipboard

{
  "affected": [],
  "aliases": [
    "CVE-2021-27862"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-130",
      "CWE-290"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2022-09-27T19:15:00Z",
    "severity": "MODERATE"
  },
  "details": "Layer 2 network filtering capabilities such as IPv6 RA guard can be bypassed using LLC/SNAP headers with invalid length and Ethernet to Wifi frame conversion (and optionally VLAN0 headers).",
  "id": "GHSA-4fhf-8ph3-pp6c",
  "modified": "2025-11-04T21:30:27Z",
  "published": "2022-09-28T00:00:18Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-27862"
    },
    {
      "type": "WEB",
      "url": "https://blog.champtar.fr/VLAN0_LLC_SNAP"
    },
    {
      "type": "WEB",
      "url": "https://datatracker.ietf.org/doc/draft-ietf-v6ops-ra-guard/08"
    },
    {
      "type": "WEB",
      "url": "https://kb.cert.org/vuls/id/855201"
    },
    {
      "type": "WEB",
      "url": "https://standards.ieee.org/ieee/802.2/1048"
    },
    {
      "type": "WEB",
      "url": "https://www.kb.cert.org/vuls/id/855201"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N",
      "type": "CVSS_V3"
    }
  ]
}

GSD-2021-27862

Vulnerability from gsd - Updated: 2023-12-13 01:23

Details

Layer 2 network filtering capabilities such as IPv6 RA guard can be bypassed using LLC/SNAP headers with invalid length and Ethernet to Wifi frame conversion (and optionally VLAN0 headers).

Aliases

CVE-2021-27862

Aliases

CVE-2021-27862

JSON

To clipboard

{
  "GSD": {
    "alias": "CVE-2021-27862",
    "id": "GSD-2021-27862",
    "references": [
      "https://www.suse.com/security/cve/CVE-2021-27862.html"
    ]
  },
  "gsd": {
    "metadata": {
      "exploitCode": "unknown",
      "remediation": "unknown",
      "reportConfidence": "confirmed",
      "type": "vulnerability"
    },
    "osvSchema": {
      "aliases": [
        "CVE-2021-27862"
      ],
      "details": "Layer 2 network filtering capabilities such as IPv6 RA guard can be bypassed using LLC/SNAP headers with invalid length and Ethernet to Wifi frame conversion (and optionally VLAN0 headers).",
      "id": "GSD-2021-27862",
      "modified": "2023-12-13T01:23:35.809492Z",
      "schema_version": "1.4.0"
    }
  },
  "namespaces": {
    "cve.org": {
      "CVE_data_meta": {
        "ASSIGNER": "cert@cert.org",
        "DATE_PUBLIC": "2022-09-27T01:00:00.000Z",
        "ID": "CVE-2021-27862",
        "STATE": "PUBLIC",
        "TITLE": "L2 network filtering bypass using stacked VLAN0 and LLC/SNAP headers with an invalid length during Ethernet to Wifi frame translation"
      },
      "affects": {
        "vendor": {
          "vendor_data": [
            {
              "product": {
                "product_data": [
                  {
                    "product_name": "802.2",
                    "version": {
                      "version_data": [
                        {
                          "version_affected": "\u003c=",
                          "version_name": "802.2h-1997",
                          "version_value": "802.2h-1997"
                        }
                      ]
                    }
                  }
                ]
              },
              "vendor_name": "IEEE"
            },
            {
              "product": {
                "product_data": [
                  {
                    "product_name": "draft-ietf-v6ops-ra-guard-08",
                    "version": {
                      "version_data": [
                        {
                          "version_affected": "\u003c=",
                          "version_name": "08",
                          "version_value": "08"
                        }
                      ]
                    }
                  }
                ]
              },
              "vendor_name": "IETF"
            }
          ]
        }
      },
      "credit": [
        {
          "lang": "eng",
          "value": "Etienne Champetier (@champtar) \u003cchampetier.etienne@gmail.com\u003e "
        }
      ],
      "data_format": "MITRE",
      "data_type": "CVE",
      "data_version": "4.0",
      "description": {
        "description_data": [
          {
            "lang": "eng",
            "value": "Layer 2 network filtering capabilities such as IPv6 RA guard can be bypassed using LLC/SNAP headers with invalid length and Ethernet to Wifi frame conversion (and optionally VLAN0 headers)."
          }
        ]
      },
      "problemtype": {
        "problemtype_data": [
          {
            "description": [
              {
                "lang": "eng",
                "value": "CWE-130 Improper Handling of Length Parameter"
              }
            ]
          },
          {
            "description": [
              {
                "lang": "eng",
                "value": "CWE-290: Authentication Bypass by Spoofing"
              }
            ]
          }
        ]
      },
      "references": {
        "reference_data": [
          {
            "name": "https://datatracker.ietf.org/doc/draft-ietf-v6ops-ra-guard/08/",
            "refsource": "MISC",
            "url": "https://datatracker.ietf.org/doc/draft-ietf-v6ops-ra-guard/08/"
          },
          {
            "name": "https://standards.ieee.org/ieee/802.2/1048/",
            "refsource": "MISC",
            "url": "https://standards.ieee.org/ieee/802.2/1048/"
          },
          {
            "name": "https://kb.cert.org/vuls/id/855201",
            "refsource": "MISC",
            "url": "https://kb.cert.org/vuls/id/855201"
          },
          {
            "name": "https://blog.champtar.fr/VLAN0_LLC_SNAP/",
            "refsource": "MISC",
            "url": "https://blog.champtar.fr/VLAN0_LLC_SNAP/"
          }
        ]
      },
      "source": {
        "discovery": "EXTERNAL"
      }
    },
    "nvd.nist.gov": {
      "configurations": {
        "CVE_data_version": "4.0",
        "nodes": [
          {
            "children": [],
            "cpe_match": [
              {
                "cpe23Uri": "cpe:2.3:a:ieee:ieee_802.2:*:*:*:*:*:*:*:*",
                "cpe_name": [],
                "versionEndIncluding": "802.2h-1997",
                "vulnerable": true
              }
            ],
            "operator": "OR"
          },
          {
            "children": [],
            "cpe_match": [
              {
                "cpe23Uri": "cpe:2.3:a:ietf:p802.1q:*:*:*:*:*:*:*:*",
                "cpe_name": [],
                "versionEndIncluding": "d1.0",
                "vulnerable": true
              }
            ],
            "operator": "OR"
          }
        ]
      },
      "cve": {
        "CVE_data_meta": {
          "ASSIGNER": "cert@cert.org",
          "ID": "CVE-2021-27862"
        },
        "data_format": "MITRE",
        "data_type": "CVE",
        "data_version": "4.0",
        "description": {
          "description_data": [
            {
              "lang": "en",
              "value": "Layer 2 network filtering capabilities such as IPv6 RA guard can be bypassed using LLC/SNAP headers with invalid length and Ethernet to Wifi frame conversion (and optionally VLAN0 headers)."
            }
          ]
        },
        "problemtype": {
          "problemtype_data": [
            {
              "description": [
                {
                  "lang": "en",
                  "value": "CWE-290"
                }
              ]
            }
          ]
        },
        "references": {
          "reference_data": [
            {
              "name": "N/A",
              "refsource": "CONFIRM",
              "tags": [
                "Vendor Advisory"
              ],
              "url": "https://standards.ieee.org/ieee/802.2/1048/"
            },
            {
              "name": "N/A",
              "refsource": "CONFIRM",
              "tags": [
                "Vendor Advisory"
              ],
              "url": "https://datatracker.ietf.org/doc/draft-ietf-v6ops-ra-guard/08/"
            },
            {
              "name": "https://kb.cert.org/vuls/id/855201",
              "refsource": "MISC",
              "tags": [],
              "url": "https://kb.cert.org/vuls/id/855201"
            },
            {
              "name": "https://blog.champtar.fr/VLAN0_LLC_SNAP/",
              "refsource": "MISC",
              "tags": [],
              "url": "https://blog.champtar.fr/VLAN0_LLC_SNAP/"
            }
          ]
        }
      },
      "impact": {
        "baseMetricV3": {
          "cvssV3": {
            "attackComplexity": "LOW",
            "attackVector": "ADJACENT_NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 4.7,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "NONE",
            "integrityImpact": "LOW",
            "privilegesRequired": "NONE",
            "scope": "CHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N",
            "version": "3.1"
          },
          "exploitabilityScore": 2.8,
          "impactScore": 1.4
        }
      },
      "lastModifiedDate": "2022-10-12T13:15Z",
      "publishedDate": "2022-09-27T19:15Z"
    }
  }
}

WID-SEC-W-2022-1551

Vulnerability from csaf_certbund - Published: 2022-09-27 22:00 - Updated: 2023-10-04 22:00

Summary

Layer 2 Netzwerksicherheitskontrollen: Mehrere Schwachstellen ermöglichen Umgehen von Sicherheitsvorkehrungen

Severity

Hoch

Scope

4 vulnerabilities in this advisory, including CVE-2021-27862.

CVE-2021-27862

Layer 2 (L2) Netzwerksicherheitskontrollen, die von Switches, Routern und Betriebssystemen genutzt werden, können durch das Stapeln von Ethernet-Protokoll-Headern umgangen werden. Ein Angreifer aus dem angrenzenden Netzwerk kann dies ausnutzen indem er manipulierte Pakete über anfällige Geräte sendet. In der Folge kann er einen Denial-of-Service- oder einen Man-in-the-Middle Angriff gegen ein Zielnetzwerk durchzuführen.

Known affected: 10 products

Open the full advisory

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

CVE-2021-27862 (GCVE-0-2021-27862)

CISCO-SA-VU855201-J3Z8CKTX

FKIE_CVE-2021-27862

GHSA-4FHF-8PH3-PP6C

GSD-2021-27862

WID-SEC-W-2022-1551

Tags

Sightings

Nomenclature

Related by attack behaviour