FKIE_CVE-2026-34827

Vulnerability from fkie_nvd - Published: 2026-04-02 18:16 - Updated: 2026-07-24 21:10
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
Rack is a modular Ruby web server interface. From versions 3.0.0.beta1 to before 3.1.21, and 3.2.0 to before 3.2.6, Rack::Multipart::Parser#handle_mime_head parses quoted multipart parameters such as Content-Disposition: form-data; name="..." using repeated String#index searches combined with String#slice! prefix deletion. For escape-heavy quoted values, this causes super-linear processing. An unauthenticated attacker can send a crafted multipart/form-data request containing many parts with long backslash-escaped parameter values to trigger excessive CPU usage during multipart parsing. This results in a denial of service condition in Rack applications that accept multipart form data. This issue has been patched in versions 3.1.21 and 3.2.6.
References
security-advisories@github.comhttps://github.com/rack/rack/security/advisories/GHSA-v6x5-cg8r-vv6xMitigation, Vendor Advisory
0b0ca135-0b70-47e7-9f44-1890c2a1c46chttps://access.redhat.com/security/cve/CVE-2026-34827
0b0ca135-0b70-47e7-9f44-1890c2a1c46chttps://bugzilla.redhat.com/show_bug.cgi?id=2454501
0b0ca135-0b70-47e7-9f44-1890c2a1c46chttps://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-34827.json
Impacted products
Vendor Product Version
rack rack *
rack rack *
To clipboard 

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    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
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              "criteria": "cpe:2.3:a:rack:rack:*:*:*:*:*:ruby:*:*",
              "matchCriteriaId": "6948AAA6-873D-46BA-AA22-4C81138128E1",
              "versionEndExcluding": "3.1.21",
              "versionStartIncluding": "3.0.0",
              "vulnerable": true
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          "negate": false,
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  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Rack is a modular Ruby web server interface. From versions 3.0.0.beta1 to before 3.1.21, and 3.2.0 to before 3.2.6, Rack::Multipart::Parser#handle_mime_head parses quoted multipart parameters such as Content-Disposition: form-data; name=\"...\" using repeated String#index searches combined with String#slice! prefix deletion. For escape-heavy quoted values, this causes super-linear processing. An unauthenticated attacker can send a crafted multipart/form-data request containing many parts with long backslash-escaped parameter values to trigger excessive CPU usage during multipart parsing. This results in a denial of service condition in Rack applications that accept multipart form data. This issue has been patched in versions 3.1.21 and 3.2.6."
    },
    {
      "lang": "es",
      "value": "Rack es una interfaz modular de servidor web Ruby. Desde las versiones 3.0.0.beta1 hasta antes de la 3.1.21, y de la 3.2.0 hasta antes de la 3.2.6, Rack::Multipart::Parser#handle_mime_head analiza par\u00e1metros multipart entrecomillados como Content-Disposition: form-data; name=\"...\" utilizando b\u00fasquedas repetidas de String#index combinadas con la eliminaci\u00f3n de prefijos de String#slice!. Para valores entrecomillados con muchas secuencias de escape, esto causa un procesamiento superlineal. Un atacante no autenticado puede enviar una solicitud multipart/form-data manipulada que contiene muchas partes con valores de par\u00e1metros largos escapados con barra invertida para desencadenar un uso excesivo de la CPU durante el an\u00e1lisis multipart. Esto resulta en una condici\u00f3n de denegaci\u00f3n de servicio en aplicaciones Rack que aceptan datos de formulario multipart. Este problema ha sido parcheado en las versiones 3.1.21 y 3.2.6."
    }
  ],
  "id": "CVE-2026-34827",
  "lastModified": "2026-07-24T21:10:00.143",
  "metrics": {
    "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"
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        "impactScore": 3.6,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      },
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          "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",
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        "impactScore": 3.6,
        "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
        "type": "Secondary"
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        "ssvcData": {
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          "options": [
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            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-04-02T18:42:04.834994Z",
          "version": "2.0.3"
        }
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  "published": "2026-04-02T18:16:33.490",
  "references": [
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      "tags": [
        "Mitigation",
        "Vendor Advisory"
      ],
      "url": "https://github.com/rack/rack/security/advisories/GHSA-v6x5-cg8r-vv6x"
    },
    {
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
      "url": "https://access.redhat.com/security/cve/CVE-2026-34827"
    },
    {
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
      "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2454501"
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      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-34827.json"
    }
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  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
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          "lang": "en",
          "value": "CWE-400"
        },
        {
          "lang": "en",
          "value": "CWE-407"
        },
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          "value": "CWE-770"
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      "source": "security-advisories@github.com",
      "type": "Secondary"
    },
    {
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          "value": "CWE-770"
        }
      ],
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
      "type": "Secondary"
    }
  ]
}



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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
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