FKIE_CVE-2021-32671

Vulnerability from fkie_nvd - Published: 2021-06-07 22:15 - Updated: 2026-06-17 03:53
Severity
10.0 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
10.0 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Summary
Flarum is a forum software for building communities. Flarum's translation system allowed for string inputs to be converted into HTML DOM nodes when rendered. This change was made after v0.1.0-beta.16 (our last beta before v1.0.0) and was not noticed or documented. This allowed for any user to type malicious HTML markup within certain user input fields and have this execute on client browsers. The example which led to the discovery of this vulnerability was in the forum search box. Entering faux-malicious HTML markup, such as <script>alert('test')</script> resulted in an alert box appearing on the forum. This attack could also be modified to perform AJAX requests on behalf of a user, possibly deleting discussions, modifying their settings or profile, or even modifying settings on the Admin panel if the attack was targetted towards a privileged user. All Flarum communities that run flarum v1.0.0 or v1.0.1 are impacted. The vulnerability has been fixed and published as flarum/core v1.0.2. All communities running Flarum v1.0 have to upgrade as soon as possible to v1.0.2.
References
security-advisories@github.comhttps://github.com/flarum/core/commit/440bed81b8019dff00642c8f493b4909d505a28aPatch, Third Party Advisory
security-advisories@github.comhttps://github.com/flarum/core/security/advisories/GHSA-5qjq-69w6-fg57Third Party Advisory
security-advisories@github.comhttps://packagist.org/packages/flarum/coreProduct, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108https://github.com/flarum/core/commit/440bed81b8019dff00642c8f493b4909d505a28aPatch, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108https://github.com/flarum/core/security/advisories/GHSA-5qjq-69w6-fg57Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108https://packagist.org/packages/flarum/coreProduct, Third Party Advisory
Impacted products
Vendor Product Version
flarum flarum 1.0.0
flarum flarum 1.0.1
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "core",
          "vendor": "flarum",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 1.0.0, \u003c 1.0.2"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:flarum:flarum:1.0.0:*:*:*:*:*:*:*",
              "matchCriteriaId": "3241FCD1-F5B7-4447-8FF9-6C02EEBB846D",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:flarum:flarum:1.0.1:*:*:*:*:*:*:*",
              "matchCriteriaId": "48C22B7B-9BD3-4AA4-9DB7-1CE3D837E5C2",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Flarum is a forum software for building communities. Flarum\u0027s translation system allowed for string inputs to be converted into HTML DOM nodes when rendered. This change was made after v0.1.0-beta.16 (our last beta before v1.0.0) and was not noticed or documented. This allowed for any user to type malicious HTML markup within certain user input fields and have this execute on client browsers. The example which led to the discovery of this vulnerability was in the forum search box. Entering faux-malicious HTML markup, such as \u003cscript\u003ealert(\u0027test\u0027)\u003c/script\u003e resulted in an alert box appearing on the forum. This attack could also be modified to perform AJAX requests on behalf of a user, possibly deleting discussions, modifying their settings or profile, or even modifying settings on the Admin panel if the attack was targetted towards a privileged user. All Flarum communities that run flarum v1.0.0 or v1.0.1 are impacted. The vulnerability has been fixed and published as flarum/core v1.0.2. All communities running Flarum v1.0 have to upgrade as soon as possible to v1.0.2."
    },
    {
      "lang": "es",
      "value": "\"Flarum es un software de foros para construir comunidades. El sistema de traducci\u00f3n de Flarum permit\u00eda que las entradas de cadena se convirtieran en nodos HTML DOM cuando son renderizadas. Este cambio se realiz\u00f3 despu\u00e9s de la versi\u00f3n v0.1.0-beta.16 (nuestra \u00faltima beta versiones anteriores a v1.0.0) y no fue advertido ni documentado. Esto permit\u00eda que cualquier usuario escribiera marcas HTML maliciosas dentro de determinados campos de entrada del usuario y que \u00e9stas se ejecutaran en los navegadores de los clientes. El ejemplo que condujo al descubrimiento de esta vulnerabilidad fue en el cuadro de b\u00fasqueda del foro. La introducci\u00f3n de marcas HTML falsamente maliciosas, como (script)alert(\"\"test\"\")(/script) resultado a la aparici\u00f3n de un cuadro de alerta en el foro. Este ataque tambi\u00e9n pod\u00eda ser modificado para llevar a cabo peticiones AJAX en nombre de un usuario, posiblemente borrando discusiones, modificando su configuraci\u00f3n o perfil, o incluso modificando la configuraci\u00f3n en el panel de administraci\u00f3n si el ataque estaba dirigido a un usuario privilegiado. Todas las comunidades de Flarum que ejecutan flarum versiones v1.0.0 o v1.0.1 est\u00e1n afectadas. La vulnerabilidad ha sido corregida y publicada como flarum/core versi\u00f3n v1.0.2. Todas las comunidades que ejecutan Flarum versi\u00f3n v1.0, tienen que actualizar lo antes posible a la v1.0.2"
    }
  ],
  "id": "CVE-2021-32671",
  "lastModified": "2026-06-17T03:53:23.417",
  "metrics": {
    "cvssMetricV2": [
      {
        "acInsufInfo": false,
        "baseSeverity": "MEDIUM",
        "cvssData": {
          "accessComplexity": "MEDIUM",
          "accessVector": "NETWORK",
          "authentication": "NONE",
          "availabilityImpact": "NONE",
          "baseScore": 4.3,
          "confidentialityImpact": "NONE",
          "integrityImpact": "PARTIAL",
          "vectorString": "AV:N/AC:M/Au:N/C:N/I:P/A:N",
          "version": "2.0"
        },
        "exploitabilityScore": 8.6,
        "impactScore": 2.9,
        "obtainAllPrivilege": false,
        "obtainOtherPrivilege": false,
        "obtainUserPrivilege": false,
        "source": "nvd@nist.gov",
        "type": "Primary",
        "userInteractionRequired": true
      }
    ],
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 10.0,
          "baseSeverity": "CRITICAL",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "CHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 6.0,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      },
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 10.0,
          "baseSeverity": "CRITICAL",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "CHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 6.0,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ]
  },
  "published": "2021-06-07T22:15:07.743",
  "references": [
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ],
      "url": "https://github.com/flarum/core/commit/440bed81b8019dff00642c8f493b4909d505a28a"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Third Party Advisory"
      ],
      "url": "https://github.com/flarum/core/security/advisories/GHSA-5qjq-69w6-fg57"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Product",
        "Third Party Advisory"
      ],
      "url": "https://packagist.org/packages/flarum/core"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ],
      "url": "https://github.com/flarum/core/commit/440bed81b8019dff00642c8f493b4909d505a28a"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Third Party Advisory"
      ],
      "url": "https://github.com/flarum/core/security/advisories/GHSA-5qjq-69w6-fg57"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Product",
        "Third Party Advisory"
      ],
      "url": "https://packagist.org/packages/flarum/core"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-79"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}



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