Vulnerability-Lookup

FKIE_CVE-2021-43826

Vulnerability from fkie_nvd - Published: 2022-02-22 23:15 - Updated: 2026-06-17 04:11

Severity

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

Summary

Envoy is an open source edge and service proxy, designed for cloud-native applications. In affected versions of Envoy a crash occurs when configured for :ref:`upstream tunneling <envoy_v3_api_field_extensions.filters.network.tcp_proxy.v3.TcpProxy.tunneling_config>` and the downstream connection disconnects while the the upstream connection or http/2 stream is still being established. There are no workarounds for this issue. Users are advised to upgrade.

References

URL	Tags
security-advisories@github.com	https://github.com/envoyproxy/envoy/commit/ce0ae309057a216aba031aff81c445c90c6ef145	Patch, Third Party Advisory
security-advisories@github.com	https://github.com/envoyproxy/envoy/security/advisories/GHSA-cmx3-fvgf-83mf	Issue Tracking, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108	https://github.com/envoyproxy/envoy/commit/ce0ae309057a216aba031aff81c445c90c6ef145	Patch, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108	https://github.com/envoyproxy/envoy/security/advisories/GHSA-cmx3-fvgf-83mf	Issue Tracking, Third Party Advisory

Impacted products

Vendor	Product	Version
envoyproxy	envoy	*
envoyproxy	envoy	*
envoyproxy	envoy	*
envoyproxy	envoy	*

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "envoy",
          "vendor": "envoyproxy",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 1.18.6"
            },
            {
              "status": "affected",
              "version": "\u003e= 1.19.0, \u003c 1.19.3"
            },
            {
              "status": "affected",
              "version": "\u003e= 1.20.0, \u003c 1.20.2"
            },
            {
              "status": "affected",
              "version": "\u003e= 1.21.0, \u003c 1.21.1"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "0EFC93D0-C206-417C-81D0-F18145E3D768",
              "versionEndExcluding": "1.18.6",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "2812AC62-44B5-4077-862D-A221CD88981D",
              "versionEndExcluding": "1.19.3",
              "versionStartIncluding": "1.19.0",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "F5441B2D-F807-4ED9-AFB9-ED4DE07CE5F8",
              "versionEndExcluding": "1.20.2",
              "versionStartIncluding": "1.20.0",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "83895D03-DAD1-4893-8A1C-F9143DEEC172",
              "versionEndExcluding": "1.21.1",
              "versionStartIncluding": "1.21.0",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Envoy is an open source edge and service proxy, designed for cloud-native applications. In affected versions of Envoy a crash occurs when configured for :ref:`upstream tunneling \u003cenvoy_v3_api_field_extensions.filters.network.tcp_proxy.v3.TcpProxy.tunneling_config\u003e` and the downstream connection disconnects while the the upstream connection or http/2 stream is still being established. There are no workarounds for this issue. Users are advised to upgrade."
    },
    {
      "lang": "es",
      "value": "Envoy es un proxy de borde y servicio de c\u00f3digo abierto, dise\u00f1ado para aplicaciones nativas de la nube. En las versiones afectadas de Envoy se produce un bloqueo cuando es configurada para :ref:\"upstream tunneling (envoy_v3_api_field_extensions.filters.network.tcp_proxy.v3.TcpProxy.tunneling_config)\" y la conexi\u00f3n de bajada es desconectada mientras sigue estableciendo la conexi\u00f3n de subida o el flujo http/2. No se presentan medidas de mitigaci\u00f3n para este problema. Es recomendado a usuarios actualizar"
    }
  ],
  "id": "CVE-2021-43826",
  "lastModified": "2026-06-17T04:11:31.247",
  "metrics": {
    "cvssMetricV2": [
      {
        "acInsufInfo": false,
        "baseSeverity": "MEDIUM",
        "cvssData": {
          "accessComplexity": "MEDIUM",
          "accessVector": "NETWORK",
          "authentication": "NONE",
          "availabilityImpact": "PARTIAL",
          "baseScore": 4.3,
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "vectorString": "AV:N/AC:M/Au:N/C:N/I:N/A:P",
          "version": "2.0"
        },
        "exploitabilityScore": 8.6,
        "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": "security-advisories@github.com",
        "type": "Secondary"
      },
      {
        "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"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2021-43826",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2025-04-23T15:57:19.863004Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2022-02-22T23:15:10.957",
  "references": [
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ],
      "url": "https://github.com/envoyproxy/envoy/commit/ce0ae309057a216aba031aff81c445c90c6ef145"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Issue Tracking",
        "Third Party Advisory"
      ],
      "url": "https://github.com/envoyproxy/envoy/security/advisories/GHSA-cmx3-fvgf-83mf"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ],
      "url": "https://github.com/envoyproxy/envoy/commit/ce0ae309057a216aba031aff81c445c90c6ef145"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Issue Tracking",
        "Third Party Advisory"
      ],
      "url": "https://github.com/envoyproxy/envoy/security/advisories/GHSA-cmx3-fvgf-83mf"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-416"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}

CVE-2021-43826 (GCVE-0-2021-43826)

Vulnerability from cvelistv5 – Published: 2022-02-22 22:45 – Updated: 2025-04-23 19:01

Title

Crash when tunneling TCP over HTTP in Envoy

Summary

Severity

7.5 (High)


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

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2025-04-23 15:57 UTC

CWE

CWE-416 - Use After Free

Assigner

GitHub_M mitre root

References

2 references

URL	Tags
https://github.com/envoyproxy/envoy/security/advi…	x_refsource_CONFIRM
https://github.com/envoyproxy/envoy/commit/ce0ae3…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
envoyproxy	envoy	Affected: < 1.18.6 Affected: >= 1.19.0, < 1.19.3 Affected: >= 1.20.0, < 1.20.2 Affected: >= 1.21.0, < 1.21.1

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "providerMetadata": {
          "dateUpdated": "2024-08-04T04:03:09.047Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
          "shortName": "CVE"
        },
        "references": [
          {
            "tags": [
              "x_refsource_CONFIRM",
              "x_transferred"
            ],
            "url": "https://github.com/envoyproxy/envoy/security/advisories/GHSA-cmx3-fvgf-83mf"
          },
          {
            "tags": [
              "x_refsource_MISC",
              "x_transferred"
            ],
            "url": "https://github.com/envoyproxy/envoy/commit/ce0ae309057a216aba031aff81c445c90c6ef145"
          }
        ],
        "title": "CVE Program Container"
      },
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2021-43826",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2025-04-23T15:57:19.863004Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2025-04-23T19:01:09.708Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "envoy",
          "vendor": "envoyproxy",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 1.18.6"
            },
            {
              "status": "affected",
              "version": "\u003e= 1.19.0, \u003c 1.19.3"
            },
            {
              "status": "affected",
              "version": "\u003e= 1.20.0, \u003c 1.20.2"
            },
            {
              "status": "affected",
              "version": "\u003e= 1.21.0, \u003c 1.21.1"
            }
          ]
        }
      ],
      "descriptions": [
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          "lang": "en",
          "value": "Envoy is an open source edge and service proxy, designed for cloud-native applications. In affected versions of Envoy a crash occurs when configured for :ref:`upstream tunneling \u003cenvoy_v3_api_field_extensions.filters.network.tcp_proxy.v3.TcpProxy.tunneling_config\u003e` and the downstream connection disconnects while the the upstream connection or http/2 stream is still being established. There are no workarounds for this issue. Users are advised to upgrade."
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      ],
      "metrics": [
        {
          "cvssV3_1": {
            "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"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
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              "description": "CWE-416: Use After Free",
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              "type": "CWE"
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      "providerMetadata": {
        "dateUpdated": "2022-02-22T22:45:22.000Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
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      "references": [
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          ],
          "url": "https://github.com/envoyproxy/envoy/security/advisories/GHSA-cmx3-fvgf-83mf"
        },
        {
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/envoyproxy/envoy/commit/ce0ae309057a216aba031aff81c445c90c6ef145"
        }
      ],
      "source": {
        "advisory": "GHSA-cmx3-fvgf-83mf",
        "discovery": "UNKNOWN"
      },
      "title": "Crash when tunneling TCP over HTTP in Envoy",
      "x_legacyV4Record": {
        "CVE_data_meta": {
          "ASSIGNER": "security-advisories@github.com",
          "ID": "CVE-2021-43826",
          "STATE": "PUBLIC",
          "TITLE": "Crash when tunneling TCP over HTTP in Envoy"
        },
        "affects": {
          "vendor": {
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              {
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                  "product_data": [
                    {
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                      "version": {
                        "version_data": [
                          {
                            "version_value": "\u003c 1.18.6"
                          },
                          {
                            "version_value": "\u003e= 1.19.0, \u003c 1.19.3"
                          },
                          {
                            "version_value": "\u003e= 1.20.0, \u003c 1.20.2"
                          },
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                            "version_value": "\u003e= 1.21.0, \u003c 1.21.1"
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          ]
        },
        "impact": {
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            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
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            "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"
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        "problemtype": {
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  "cveMetadata": {
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    "assignerShortName": "GitHub_M",
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    "datePublished": "2022-02-22T22:45:22.000Z",
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    "dateUpdated": "2025-04-23T19:01:09.708Z",
    "state": "PUBLISHED"
  },
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  "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.

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.

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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.

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FKIE_CVE-2021-43826

CVE-2021-43826 (GCVE-0-2021-43826)

Tags

Sightings

Nomenclature

Related by attack behaviour