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FKIE_CVE-2021-36740

Vulnerability from fkie_nvd - Published: 2021-07-14 17:15 - Updated: 2026-06-17 03:59
Severity
6.5 (Medium) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Summary
Varnish Cache, with HTTP/2 enabled, allows request smuggling and VCL authorization bypass via a large Content-Length header for a POST request. This affects Varnish Enterprise 6.0.x before 6.0.8r3, and Varnish Cache 5.x and 6.x before 6.5.2, 6.6.x before 6.6.1, and 6.0 LTS before 6.0.8.
References
cve@mitre.orghttps://docs.varnish-software.com/security/VSV00007/Mitigation, Vendor Advisory
cve@mitre.orghttps://github.com/varnishcache/varnish-cache/commit/82b0a629f60136e76112c6f2c6372cce77b683bePatch, Third Party Advisory
cve@mitre.orghttps://github.com/varnishcache/varnish-cache/commit/9be22198e258d0e7a5c41f4291792214a29405cfPatch, Third Party Advisory
cve@mitre.orghttps://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/THV2DQA2GS65HUCKK4KSD2XLN3AAQ2V5/
cve@mitre.orghttps://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZHBNLDEOTGYRIEQZBWV7F6VPYS4O2AAK/
cve@mitre.orghttps://varnish-cache.org/security/VSV00007.htmlMitigation, Vendor Advisory
cve@mitre.orghttps://www.debian.org/security/2022/dsa-5088Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108https://docs.varnish-software.com/security/VSV00007/Mitigation, Vendor Advisory
af854a3a-2127-422b-91ae-364da2661108https://github.com/varnishcache/varnish-cache/commit/82b0a629f60136e76112c6f2c6372cce77b683bePatch, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108https://github.com/varnishcache/varnish-cache/commit/9be22198e258d0e7a5c41f4291792214a29405cfPatch, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/THV2DQA2GS65HUCKK4KSD2XLN3AAQ2V5/
af854a3a-2127-422b-91ae-364da2661108https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZHBNLDEOTGYRIEQZBWV7F6VPYS4O2AAK/
af854a3a-2127-422b-91ae-364da2661108https://varnish-cache.org/security/VSV00007.htmlMitigation, Vendor Advisory
af854a3a-2127-422b-91ae-364da2661108https://www.debian.org/security/2022/dsa-5088Third Party Advisory
Impacted products
Vendor Product Version
varnish-cache varnish_cache *
varnish-cache varnish_cache 6.0.8
varnish-cache varnish_cache 6.0.8
varnish-software varnish_cache *
varnish-software varnish_cache *
varnish_cache_project varnish_cache *
varnish_cache_project varnish_cache *
fedoraproject fedora 33
fedoraproject fedora 34
debian debian_linux 10.0
debian debian_linux 11.0
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "n/a",
          "vendor": "n/a",
          "versions": [
            {
              "status": "affected",
              "version": "n/a"
            }
          ]
        }
      ],
      "source": "cve@mitre.org"
    }
  ],
  "configurations": [
    {
      "nodes": [
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          "cpeMatch": [
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              "versionEndExcluding": "6.0.8",
              "versionStartIncluding": "6.0.0",
              "vulnerable": true
            },
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              "versionEndIncluding": "6.0.5",
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              "versionEndIncluding": "5.2.1",
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              "versionEndIncluding": "6.6.0",
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            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    },
    {
      "nodes": [
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          "cpeMatch": [
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              "criteria": "cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*",
              "matchCriteriaId": "E460AA51-FCDA-46B9-AE97-E6676AA5E194",
              "vulnerable": true
            },
            {
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      ]
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  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Varnish Cache, with HTTP/2 enabled, allows request smuggling and VCL authorization bypass via a large Content-Length header for a POST request. This affects Varnish Enterprise 6.0.x before 6.0.8r3, and Varnish Cache 5.x and 6.x before 6.5.2, 6.6.x before 6.6.1, and 6.0 LTS before 6.0.8."
    },
    {
      "lang": "es",
      "value": "Varnish Cache, con HTTP/2 habilitado, permite el contrabando de peticiones y la omisi\u00f3n de autorizaci\u00f3n de VCL por medio de un encabezado Content-Length grande para una petici\u00f3n POST. Esto afecta a Varnish Enterprise versiones 6.0.x anteriores a 6.0.8r3, y Varnish Cache versiones 5.xy 6.x anteriores a 6.5.2, versiones 6.6.x anteriores a 6.6.1 y versiones 6.0 LTS anteriores a 6.0.8"
    }
  ],
  "id": "CVE-2021-36740",
  "lastModified": "2026-06-17T03:59:05.367",
  "metrics": {
    "cvssMetricV2": [
      {
        "acInsufInfo": false,
        "baseSeverity": "MEDIUM",
        "cvssData": {
          "accessComplexity": "LOW",
          "accessVector": "NETWORK",
          "authentication": "NONE",
          "availabilityImpact": "NONE",
          "baseScore": 6.4,
          "confidentialityImpact": "PARTIAL",
          "integrityImpact": "PARTIAL",
          "vectorString": "AV:N/AC:L/Au:N/C:P/I:P/A:N",
          "version": "2.0"
        },
        "exploitabilityScore": 10.0,
        "impactScore": 4.9,
        "obtainAllPrivilege": false,
        "obtainOtherPrivilege": false,
        "obtainUserPrivilege": false,
        "source": "nvd@nist.gov",
        "type": "Primary",
        "userInteractionRequired": false
      }
    ],
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 6.5,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "LOW",
          "integrityImpact": "LOW",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 2.5,
        "source": "nvd@nist.gov",
        "type": "Primary"
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    ]
  },
  "published": "2021-07-14T17:15:08.253",
  "references": [
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      "source": "cve@mitre.org",
      "tags": [
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      "url": "https://docs.varnish-software.com/security/VSV00007/"
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    {
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    },
    {
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          "value": "CWE-444"
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      "source": "nvd@nist.gov",
      "type": "Primary"
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  ]
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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.


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.