FKIE_CVE-2021-39191

Vulnerability from fkie_nvd - Published: 2021-09-03 14:15 - Updated: 2026-06-17 04:03
Severity
4.7 (Medium) - CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N
6.1 (Medium) - CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Summary
mod_auth_openidc is an authentication/authorization module for the Apache 2.x HTTP server that functions as an OpenID Connect Relying Party, authenticating users against an OpenID Connect Provider. In versions prior to 2.4.9.4, the 3rd-party init SSO functionality of mod_auth_openidc was reported to be vulnerable to an open redirect attack by supplying a crafted URL in the `target_link_uri` parameter. A patch in version 2.4.9.4 made it so that the `OIDCRedirectURLsAllowed` setting must be applied to the `target_link_uri` parameter. There are no known workarounds aside from upgrading to a patched version.
References
security-advisories@github.comhttps://github.com/zmartzone/mod_auth_openidc/commit/03e6bfb446f4e3f27c003d30d6a433e5dd8e2b3dPatch, Third Party Advisory
security-advisories@github.comhttps://github.com/zmartzone/mod_auth_openidc/issues/672Exploit
security-advisories@github.comhttps://github.com/zmartzone/mod_auth_openidc/releases/tag/v2.4.9.4Release Notes
security-advisories@github.comhttps://github.com/zmartzone/mod_auth_openidc/security/advisories/GHSA-2pgf-8h6h-gqg2Vendor Advisory
security-advisories@github.comhttps://lists.debian.org/debian-lts-announce/2023/07/msg00020.htmlMailing List
security-advisories@github.comhttps://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/32RGPW5LZDLDTB7MKZIGAHPSLFOUNWR5/
security-advisories@github.comhttps://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RHXO4O4G2UQS7X6OQJCVZKHZAQ7SAIFB/
af854a3a-2127-422b-91ae-364da2661108https://github.com/zmartzone/mod_auth_openidc/commit/03e6bfb446f4e3f27c003d30d6a433e5dd8e2b3dPatch, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108https://github.com/zmartzone/mod_auth_openidc/issues/672Exploit
af854a3a-2127-422b-91ae-364da2661108https://github.com/zmartzone/mod_auth_openidc/releases/tag/v2.4.9.4Release Notes
af854a3a-2127-422b-91ae-364da2661108https://github.com/zmartzone/mod_auth_openidc/security/advisories/GHSA-2pgf-8h6h-gqg2Vendor Advisory
af854a3a-2127-422b-91ae-364da2661108https://lists.debian.org/debian-lts-announce/2023/07/msg00020.htmlMailing List
af854a3a-2127-422b-91ae-364da2661108https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/32RGPW5LZDLDTB7MKZIGAHPSLFOUNWR5/
af854a3a-2127-422b-91ae-364da2661108https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RHXO4O4G2UQS7X6OQJCVZKHZAQ7SAIFB/
Impacted products
Vendor Product Version
openidc mod_auth_openidc *
fedoraproject fedora 35
fedoraproject fedora 36
debian debian_linux 10.0
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "mod_auth_openidc",
          "vendor": "zmartzone",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c=2.4.9.3"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:openidc:mod_auth_openidc:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "93E4D476-0087-4EBC-82E8-6B233FCC291A",
              "versionEndExcluding": "2.4.9.4",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    },
    {
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              "matchCriteriaId": "80E516C0-98A4-4ADE-B69F-66A772E2BAAA",
              "vulnerable": true
            },
            {
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              "matchCriteriaId": "5C675112-476C-4D7C-BCB9-A2FB2D0BC9FD",
              "vulnerable": true
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          "operator": "OR"
        }
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              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "mod_auth_openidc is an authentication/authorization module for the Apache 2.x HTTP server that functions as an OpenID Connect Relying Party, authenticating users against an OpenID Connect Provider. In versions prior to 2.4.9.4, the 3rd-party init SSO functionality of mod_auth_openidc was reported to be vulnerable to an open redirect attack by supplying a crafted URL in the `target_link_uri` parameter. A patch in version 2.4.9.4 made it so that the `OIDCRedirectURLsAllowed` setting must be applied to the `target_link_uri` parameter. There are no known workarounds aside from upgrading to a patched version."
    },
    {
      "lang": "es",
      "value": "mod_auth_openidc es un m\u00f3dulo de autenticaci\u00f3n/autorizaci\u00f3n para el servidor HTTP Apache versi\u00f3n 2.x, que funciona como OpenID Connect Relying Party, autenticando a usuarios contra un proveedor de OpenID Connect. En las versiones anteriores a 2.4.9.4, la funcionalidad de SSO init de terceros de mod_auth_openidc era vulnerable a un ataque de redirecci\u00f3n abierta mediante el suministro de una URL dise\u00f1ada en el par\u00e1metro \"target_link_uri\". Un parche en la versi\u00f3n 2.4.9.4 hizo que la configuraci\u00f3n \"OIDCRedirectURLsAllowed\" se aplicara al par\u00e1metro \"target_link_uri\". No se conocen soluciones aparte de la actualizaci\u00f3n a una versi\u00f3n parcheada"
    }
  ],
  "id": "CVE-2021-39191",
  "lastModified": "2026-06-17T04:03:16.853",
  "metrics": {
    "cvssMetricV2": [
      {
        "acInsufInfo": false,
        "baseSeverity": "MEDIUM",
        "cvssData": {
          "accessComplexity": "MEDIUM",
          "accessVector": "NETWORK",
          "authentication": "NONE",
          "availabilityImpact": "NONE",
          "baseScore": 5.8,
          "confidentialityImpact": "PARTIAL",
          "integrityImpact": "PARTIAL",
          "vectorString": "AV:N/AC:M/Au:N/C:P/I:P/A:N",
          "version": "2.0"
        },
        "exploitabilityScore": 8.6,
        "impactScore": 4.9,
        "obtainAllPrivilege": false,
        "obtainOtherPrivilege": false,
        "obtainUserPrivilege": false,
        "source": "nvd@nist.gov",
        "type": "Primary",
        "userInteractionRequired": true
      }
    ],
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 4.7,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "LOW",
          "privilegesRequired": "NONE",
          "scope": "CHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N",
          "version": "3.1"
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        "cvssData": {
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          "attackVector": "NETWORK",
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          "baseScore": 6.1,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "LOW",
          "integrityImpact": "LOW",
          "privilegesRequired": "NONE",
          "scope": "CHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
          "version": "3.1"
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        "exploitabilityScore": 2.8,
        "impactScore": 2.7,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
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  },
  "published": "2021-09-03T14:15:07.210",
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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.



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