FKIE_CVE-2026-27820

Vulnerability from fkie_nvd - Published: 2026-04-16 18:16 - Updated: 2026-10-26 21:10
Severity
9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Summary
zlib is a Ruby interface for the zlib compression/decompression library. Versions 3.0.0 and below, 3.1.0, 3.1.1, 3.2.0 and 3.2.1 contain a buffer overflow vulnerability in the Zlib::GzipReader. The zstream_buffer_ungets function prepends caller-provided bytes ahead of previously produced output but fails to guarantee the backing Ruby string has enough capacity before the memmove shifts the existing data. This can lead to memory corruption when the buffer length exceeds capacity. This issue has been fixed in versions 3.0.1, 3.1.2 and 3.2.3.
References
security-advisories@github.comhttps://github.com/ruby/zlib/security/advisories/GHSA-g857-hhfv-j68wVendor Advisory
security-advisories@github.comhttps://hackerone.com/reports/3467067Permissions Required
Impacted products
Vendor Product Version
ruby-lang zlib *
ruby-lang zlib *
ruby-lang zlib *
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "zlib",
          "vendor": "ruby",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 3.0.1"
            },
            {
              "status": "affected",
              "version": "\u003e= 3.1.0, \u003c 3.1.2"
            },
            {
              "status": "affected",
              "version": "\u003e= 3.2.0, \u003c 3.2.3"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "configurations": [
    {
      "nodes": [
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          "cpeMatch": [
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              "criteria": "cpe:2.3:a:ruby-lang:zlib:*:*:*:*:*:ruby:*:*",
              "matchCriteriaId": "5DE8B341-809F-4E90-AA03-28B264F35B52",
              "versionEndExcluding": "3.0.1",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:ruby-lang:zlib:*:*:*:*:*:ruby:*:*",
              "matchCriteriaId": "C9B291C1-492A-4684-BE65-36D10D28679F",
              "versionEndExcluding": "3.1.2",
              "versionStartIncluding": "3.1.0",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:ruby-lang:zlib:*:*:*:*:*:ruby:*:*",
              "matchCriteriaId": "CD9F2E4A-7F44-43CD-8745-28BC10E5FA04",
              "versionEndExcluding": "3.2.3",
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              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "zlib is a Ruby interface for the zlib compression/decompression library. Versions 3.0.0 and below, 3.1.0, 3.1.1, 3.2.0 and 3.2.1 contain a buffer overflow vulnerability in the Zlib::GzipReader. The zstream_buffer_ungets function prepends caller-provided bytes ahead of previously produced output but fails to guarantee the backing Ruby string has enough capacity before the memmove shifts the existing data. This can lead to memory corruption when the buffer length exceeds capacity. This issue has been fixed in versions 3.0.1, 3.1.2 and 3.2.3."
    },
    {
      "lang": "es",
      "value": "zlib es una interfaz Ruby para la biblioteca de compresi\u00f3n/descompresi\u00f3n zlib. Las versiones 3.0.0 e inferiores, 3.1.0, 3.1.1, 3.2.0 y 3.2.1 contienen una vulnerabilidad de desbordamiento de b\u00fafer en Zlib::GzipReader. La funci\u00f3n zstream_buffer_ungets antepone bytes proporcionados por el llamador delante de la salida producida previamente, pero no garantiza que la cadena Ruby subyacente tenga suficiente capacidad antes de que memmove desplace los datos existentes. Esto puede llevar a corrupci\u00f3n de memoria cuando la longitud del b\u00fafer excede la capacidad. Este problema ha sido solucionado en las versiones 3.0.1, 3.1.2 y 3.2.3."
    }
  ],
  "id": "CVE-2026-27820",
  "lastModified": "2026-10-26T21:10:00.170",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 9.8,
          "baseSeverity": "CRITICAL",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
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        "impactScore": 5.9,
        "source": "nvd@nist.gov",
        "type": "Primary"
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    ],
    "cvssMetricV40": [
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        "cvssData": {
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          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "PRESENT",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 1.7,
          "baseSeverity": "LOW",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "UNREPORTED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "NONE",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "NONE",
          "subIntegrityImpact": "NONE",
          "userInteraction": "NONE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
          "version": "4.0",
          "vulnAvailabilityImpact": "LOW",
          "vulnConfidentialityImpact": "NONE",
          "vulnIntegrityImpact": "NONE",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
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          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-04-16T18:20:13.051389Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-04-16T18:16:44.770",
  "references": [
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      "tags": [
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    },
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      "tags": [
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      "url": "https://hackerone.com/reports/3467067"
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  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-120"
        },
        {
          "lang": "en",
          "value": "CWE-131"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}



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