CVE-2021-22881
The Host Authorization middleware in Action Pack before 6.1.2.1, 6.0.3.5 suffers from an open redirect vulnerability. Specially crafted `Host` headers in combination with certain "allowed host" formats can cause the Host Authorization middleware in Action Pack to redirect users to a malicious website. Impacted applications will have allowed hosts with a leading dot. When an allowed host contains a leading dot, a specially crafted `Host` header can be used to redirect to a malicious website.
CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
- Puntuación base: 6.1
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 87%
- Percentil entre todas las CVEs puntuadas: 100
- Fecha de la puntuación: 6/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
💥 Exploits públicos
Hay código de explotación o plantillas de detección públicos. No es lo mismo que explotación activa confirmada (KEV), pero aumenta el riesgo: parchee con prioridad.
- Plantilla de Nuclei (detección automática y masiva) · Ruby on Rails - Open Redirect via Host Header Injection
Tecnologías afectadas (2)
CWE
- CWE-601
- CWE-601
Referencias
- http://www.openwall.com/lists/oss-security/2021/05/05/2
- http://www.openwall.com/lists/oss-security/2021/08/20/1
- http://www.openwall.com/lists/oss-security/2021/12/14/5
- https://benjamin-bouchet.com/cve-2021-22881-faille-de-securite-dans-le-middleware-hostauthorization/
- https://discuss.rubyonrails.org/t/cve-2021-22881-possible-open-redirect-in-host-authorization-middleware/77130
- https://hackerone.com/reports/1047447
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/XQ3NS4IBYE2I3MVMGAHFZBZBIZGHXHT3/
- http://www.openwall.com/lists/oss-security/2021/05/05/2
- http://www.openwall.com/lists/oss-security/2021/08/20/1
- http://www.openwall.com/lists/oss-security/2021/12/14/5
- https://benjamin-bouchet.com/cve-2021-22881-faille-de-securite-dans-le-middleware-hostauthorization/
- https://discuss.rubyonrails.org/t/cve-2021-22881-possible-open-redirect-in-host-authorization-middleware/77130
- https://hackerone.com/reports/1047447
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/XQ3NS4IBYE2I3MVMGAHFZBZBIZGHXHT3/
JSON original (NVD)
Mostrar
{
"id": "CVE-2021-22881",
"cveTags": [],
"metrics": {
"cvssMetricV2": [
{
"type": "Primary",
"source": "nvd@nist.gov",
"cvssData": {
"version": "2.0",
"baseScore": 5.8,
"accessVector": "NETWORK",
"vectorString": "AV:N/AC:M/Au:N/C:P/I:P/A:N",
"authentication": "NONE",
"integrityImpact": "PARTIAL",
"accessComplexity": "MEDIUM",
"availabilityImpact": "NONE",
"confidentialityImpact": "PARTIAL"
},
"acInsufInfo": false,
"impactScore": 4.9,
"baseSeverity": "MEDIUM",
"obtainAllPrivilege": false,
"exploitabilityScore": 8.6,
"obtainUserPrivilege": false,
"obtainOtherPrivilege": false,
"userInteractionRequired": true
}
],
"cvssMetricV31": [
{
"type": "Primary",
"source": "nvd@nist.gov",
"cvssData": {
"scope": "CHANGED",
"version": "3.1",
"baseScore": 6.1,
"attackVector": "NETWORK",
"baseSeverity": "MEDIUM",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
"integrityImpact": "LOW",
"userInteraction": "REQUIRED",
"attackComplexity": "LOW",
"availabilityImpact": "NONE",
"privilegesRequired": "NONE",
"confidentialityImpact": "LOW"
},
"impactScore": 2.7,
"exploitabilityScore": 2.8
}
]
},
"affected": [
{
"source": "support@hackerone.com",
"affectedData": [
{
"vendor": "n/a",
"product": "https://github.com/rails/rails",
"versions": [
{
"status": "affected",
"version": "Fixed in 6.1.2.1, 6.0.3.5"
}
]
}
]
}
],
"published": "2021-02-11T18:15:17.460",
"references": [
{
"url": "http://www.openwall.com/lists/oss-security/2021/05/05/2",
"tags": [
"Mailing List",
"Mitigation",
"Third Party Advisory"
],
"source": "support@hackerone.com"
},
{
"url": "http://www.openwall.com/lists/oss-security/2021/08/20/1",
"tags": [
"Mailing List",
"Mitigation",
"Third Party Advisory"
],
"source": "support@hackerone.com"
},
{
"url": "http://www.openwall.com/lists/oss-security/2021/12/14/5",
"tags": [
"Exploit",
"Mailing List",
"Patch"
],
"source": "support@hackerone.com"
},
{
"url": "https://benjamin-bouchet.com/cve-2021-22881-faille-de-securite-dans-le-middleware-hostauthorization/",
"tags": [
"Patch",
"Third Party Advisory"
],
"source": "support@hackerone.com"
},
{
"url": "https://discuss.rubyonrails.org/t/cve-2021-22881-possible-open-redirect-in-host-authorization-middleware/77130",
"tags": [
"Mitigation",
"Patch",
"Vendor Advisory"
],
"source": "support@hackerone.com"
},
{
"url": "https://hackerone.com/reports/1047447",
"tags": [
"Exploit",
"Patch",
"Third Party Advisory"
],
"source": "support@hackerone.com"
},
{
"url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/XQ3NS4IBYE2I3MVMGAHFZBZBIZGHXHT3/",
"source": "support@hackerone.com"
},
{
"url": "http://www.openwall.com/lists/oss-security/2021/05/05/2",
"tags": [
"Mailing List",
"Mitigation",
"Third Party Advisory"
],
"source": "af854a3a-2127-422b-91ae-364da2661108"
},
{
"url": "http://www.openwall.com/lists/oss-security/2021/08/20/1",
"tags": [
"Mailing List",
"Mitigation",
"Third Party Advisory"
],
"source": "af854a3a-2127-422b-91ae-364da2661108"
},
{
"url": "http://www.openwall.com/lists/oss-security/2021/12/14/5",
"tags": [
"Exploit",
"Mailing List",
"Patch"
],
"source": "af854a3a-2127-422b-91ae-364da2661108"
},
{
"url": "https://benjamin-bouchet.com/cve-2021-22881-faille-de-securite-dans-le-middleware-hostauthorization/",
"tags": [
"Patch",
"Third Party Advisory"
],
"source": "af854a3a-2127-422b-91ae-364da2661108"
},
{
"url": "https://discuss.rubyonrails.org/t/cve-2021-22881-possible-open-redirect-in-host-authorization-middleware/77130",
"tags": [
"Mitigation",
"Patch",
"Vendor Advisory"
],
"source": "af854a3a-2127-422b-91ae-364da2661108"
},
{
"url": "https://hackerone.com/reports/1047447",
"tags": [
"Exploit",
"Patch",
"Third Party Advisory"
],
"source": "af854a3a-2127-422b-91ae-364da2661108"
},
{
"url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/XQ3NS4IBYE2I3MVMGAHFZBZBIZGHXHT3/",
"source": "af854a3a-2127-422b-91ae-364da2661108"
}
],
"vulnStatus": "Modified",
"weaknesses": [
{
"type": "Secondary",
"source": "support@hackerone.com",
"description": [
{
"lang": "en",
"value": "CWE-601"
}
]
},
{
"type": "Primary",
"source": "nvd@nist.gov",
"description": [
{
"lang": "en",
"value": "CWE-601"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "The Host Authorization middleware in Action Pack before 6.1.2.1, 6.0.3.5 suffers from an open redirect vulnerability. Specially crafted `Host` headers in combination with certain \"allowed host\" formats can cause the Host Authorization middleware in Action Pack to redirect users to a malicious website. Impacted applications will have allowed hosts with a leading dot. When an allowed host contains a leading dot, a specially crafted `Host` header can be used to redirect to a malicious website."
},
{
"lang": "es",
"value": "El middleware de Autorización de Host en Action Pack versiones anteriores a 6.1.2.1, 6.0.3.5 sufre una vulnerabilidad de redireccionamiento abierto. Los encabezados \"Host\" especialmente diseñados en combinación con determinados formatos \"allowed host\" pueden causar que el middleware de Autorización del Host en Action Pack redireccione a los usuarios a un sitio web malicioso. Las aplicaciones afectadas habrán permitido hosts con un punto inicial. Cuando un host permitido contiene un punto inicial, un encabezado \"Host\" especialmente diseñado puede ser usado para redireccionar hacia un sitio web malicioso"
}
],
"lastModified": "2026-06-17T03:37:56.390",
"configurations": [
{
"nodes": [
{
"negate": false,
"cpeMatch": [
{
"criteria": "cpe:2.3:a:rubyonrails:rails:*:*:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "817BE0F5-136C-460E-816D-74B3F6663BA8",
"versionEndExcluding": "6.0.3.5",
"versionStartIncluding": "6.0.0"
},
{
"criteria": "cpe:2.3:a:rubyonrails:rails:*:*:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "98CE6993-089E-454B-8156-011E03FC3C94",
"versionEndExcluding": "6.1.2.1",
"versionStartIncluding": "6.1.0"
}
],
"operator": "OR"
}
]
},
{
"nodes": [
{
"negate": false,
"cpeMatch": [
{
"criteria": "cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "E460AA51-FCDA-46B9-AE97-E6676AA5E194"
}
],
"operator": "OR"
}
]
}
],
"sourceIdentifier": "support@hackerone.com"
}