Vulnerability-Lookup

FKIE_CVE-2021-4234

Vulnerability from fkie_nvd - Published: 2022-07-06 20:15 - Updated: 2026-06-17 04:19

Severity

7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Summary

OpenVPN Access Server 2.10 and prior versions are susceptible to resending multiple packets in a response to a reset packet sent from the client which the client again does not respond to, resulting in a limited amplification attack.

References

	URL	Tags
	security@openvpn.net	https://openvpn.net/vpn-server-resources/release-notes/#openvpn-access-server-2-11-0	Release Notes, Vendor Advisory
	af854a3a-2127-422b-91ae-364da2661108	https://openvpn.net/vpn-server-resources/release-notes/#openvpn-access-server-2-11-0	Release Notes, Vendor Advisory

Impacted products

	Vendor	Product	Version
	openvpn	openvpn_access_server	*

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "OpenVPN Access Server",
          "vendor": "n/a",
          "versions": [
            {
              "status": "affected",
              "version": "2.10 and prior version"
            }
          ]
        }
      ],
      "source": "security@openvpn.net"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:openvpn:openvpn_access_server:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "F315C5F8-CF55-4561-87FA-09A49636FDCB",
              "versionEndExcluding": "2.11.0",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "OpenVPN Access Server 2.10 and prior versions are susceptible to resending multiple packets in a response to a reset packet sent from the client which the client again does not respond to, resulting in a limited amplification attack."
    },
    {
      "lang": "es",
      "value": "OpenVPN Access Server versiones 2.10 y versiones anteriores, son susceptibles de reenviar m\u00faltiples paquetes en respuesta a un paquete de reinicio enviado desde el cliente al que \u00e9ste no responde de nuevo, resultando en un ataque de amplificaci\u00f3n limitada"
    }
  ],
  "id": "CVE-2021-4234",
  "lastModified": "2026-06-17T04:19:19.240",
  "metrics": {
    "cvssMetricV2": [
      {
        "acInsufInfo": false,
        "baseSeverity": "MEDIUM",
        "cvssData": {
          "accessComplexity": "LOW",
          "accessVector": "NETWORK",
          "authentication": "NONE",
          "availabilityImpact": "PARTIAL",
          "baseScore": 5.0,
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "vectorString": "AV:N/AC:L/Au:N/C:N/I:N/A:P",
          "version": "2.0"
        },
        "exploitabilityScore": 10.0,
        "impactScore": 2.9,
        "obtainAllPrivilege": false,
        "obtainOtherPrivilege": false,
        "obtainUserPrivilege": false,
        "source": "nvd@nist.gov",
        "type": "Primary",
        "userInteractionRequired": false
      }
    ],
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 7.5,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 3.6,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ]
  },
  "published": "2022-07-06T20:15:08.127",
  "references": [
    {
      "source": "security@openvpn.net",
      "tags": [
        "Release Notes",
        "Vendor Advisory"
      ],
      "url": "https://openvpn.net/vpn-server-resources/release-notes/#openvpn-access-server-2-11-0"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Release Notes",
        "Vendor Advisory"
      ],
      "url": "https://openvpn.net/vpn-server-resources/release-notes/#openvpn-access-server-2-11-0"
    }
  ],
  "sourceIdentifier": "security@openvpn.net",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-406"
        }
      ],
      "source": "security@openvpn.net",
      "type": "Secondary"
    },
    {
      "description": [
        {
          "lang": "en",
          "value": "NVD-CWE-Other"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}

CVE-2021-4234 (GCVE-0-2021-4234)

Vulnerability from cvelistv5 – Published: 2022-07-06 19:10 – Updated: 2024-08-03 17:23

Summary

Severity

No CVSS data available.

CWE

CWE-406 - Insufficient Control of Network Message Volume

Assigner

OpenVPN mitre root

References

1 reference

URL	Tags
https://openvpn.net/vpn-server-resources/release-…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
n/a	OpenVPN Access Server	Affected: 2.10 and prior version

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "providerMetadata": {
          "dateUpdated": "2024-08-03T17:23:09.056Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
          "shortName": "CVE"
        },
        "references": [
          {
            "tags": [
              "x_refsource_MISC",
              "x_transferred"
            ],
            "url": "https://openvpn.net/vpn-server-resources/release-notes/#openvpn-access-server-2-11-0"
          }
        ],
        "title": "CVE Program Container"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "OpenVPN Access Server",
          "vendor": "n/a",
          "versions": [
            {
              "status": "affected",
              "version": "2.10 and prior version"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "OpenVPN Access Server 2.10 and prior versions are susceptible to resending multiple packets in a response to a reset packet sent from the client which the client again does not respond to, resulting in a limited amplification attack."
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-406",
              "description": "CWE-406: Insufficient Control of Network Message Volume",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2022-07-06T19:10:17.000Z",
        "orgId": "36a55730-e66d-4d39-8ca6-3c3b3017965e",
        "shortName": "OpenVPN"
      },
      "references": [
        {
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://openvpn.net/vpn-server-resources/release-notes/#openvpn-access-server-2-11-0"
        }
      ],
      "x_legacyV4Record": {
        "CVE_data_meta": {
          "ASSIGNER": "security@openvpn.net",
          "ID": "CVE-2021-4234",
          "STATE": "PUBLIC"
        },
        "affects": {
          "vendor": {
            "vendor_data": [
              {
                "product": {
                  "product_data": [
                    {
                      "product_name": "OpenVPN Access Server",
                      "version": {
                        "version_data": [
                          {
                            "version_value": "2.10 and prior version"
                          }
                        ]
                      }
                    }
                  ]
                },
                "vendor_name": "n/a"
              }
            ]
          }
        },
        "data_format": "MITRE",
        "data_type": "CVE",
        "data_version": "4.0",
        "description": {
          "description_data": [
            {
              "lang": "eng",
              "value": "OpenVPN Access Server 2.10 and prior versions are susceptible to resending multiple packets in a response to a reset packet sent from the client which the client again does not respond to, resulting in a limited amplification attack."
            }
          ]
        },
        "problemtype": {
          "problemtype_data": [
            {
              "description": [
                {
                  "lang": "eng",
                  "value": "CWE-406: Insufficient Control of Network Message Volume"
                }
              ]
            }
          ]
        },
        "references": {
          "reference_data": [
            {
              "name": "https://openvpn.net/vpn-server-resources/release-notes/#openvpn-access-server-2-11-0",
              "refsource": "MISC",
              "url": "https://openvpn.net/vpn-server-resources/release-notes/#openvpn-access-server-2-11-0"
            }
          ]
        }
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "36a55730-e66d-4d39-8ca6-3c3b3017965e",
    "assignerShortName": "OpenVPN",
    "cveId": "CVE-2021-4234",
    "datePublished": "2022-07-06T19:10:17.000Z",
    "dateReserved": "2022-07-01T00:00:00.000Z",
    "dateUpdated": "2024-08-03T17:23:09.056Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1"
}

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.

Detection rules are retrieved from Rulezet.

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.