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  "document": {
    "aggregate_severity": {
      "text": "Critical"
    },
    "category": "csaf_vex",
    "csaf_version": "2.0",
    "distribution": {
      "text": "TuxCare License Agreement",
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        "url": "https://www.first.org/tlp/"
      }
    },
    "lang": "en",
    "notes": [
      {
        "category": "legal_disclaimer",
        "text": "This content is licensed under the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/). If you distribute this content, or a modified version of it, you must provide attribution to Cloud Linux Inc. and provide a link to the original.",
        "title": "Terms of Use"
      }
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      "contact_details": "https://tuxcare.com/contact/",
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        "category": "self",
        "summary": "Canonical URL",
        "url": "https://security.tuxcare.com/csaf/v2/els_os/debian10els/vex/2026/cve-2026-27820-els_os-debian10els.json"
      }
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      "generator": {
        "date": "2026-10-15T17:55:35Z",
        "engine": {
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      "id": "CVE-2026-27820-ELS_OS-DEBIAN10ELS",
      "initial_release_date": "2026-04-16T18:16:00Z",
      "revision_history": [
        {
          "date": "2026-04-16T18:16:00Z",
          "number": "1",
          "summary": "Initial version"
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        {
          "date": "2026-10-09T01:28:07Z",
          "number": "2",
          "summary": "Official Publication"
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        {
          "date": "2026-10-15T17:55:35Z",
          "number": "3",
          "summary": "Update document"
        }
      ],
      "status": "final",
      "version": "3"
    },
    "title": "Security update on CVE-2026-27820"
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  "vulnerabilities": [
    {
      "cve": "CVE-2026-27820",
      "cwe": {
        "id": "CWE-120",
        "name": "Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')"
      },
      "notes": [
        {
          "category": "description",
          "text": "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.",
          "title": "Vulnerability description"
        },
        {
          "category": "other",
          "text": "TuxCare has assessed that this vulnerability does not impact any currently supported TuxCare products. This evaluation may change as new information becomes available. For additional details regarding this vulnerability and affected products, refer to the provided references.",
          "title": "Statement"
        }
      ],
      "product_status": {
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          "Debian-10:zlib1g-dev-1:1.2.11.dfsg-1+deb10u2+tuxcare.els1.arm64",
          "Debian-10:zlib1g-dev-1:1.2.11.dfsg-1+deb10u2+tuxcare.els1.armel"
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      "references": [
        {
          "category": "self",
          "summary": "Canonical URL",
          "url": "https://cve.tuxcare.com/els/cve/CVE-2026-27820"
        },
        {
          "category": "external",
          "summary": "https://github.com/ruby/zlib/security/advisories/GHSA-g857-hhfv-j68w",
          "url": "https://github.com/ruby/zlib/security/advisories/GHSA-g857-hhfv-j68w"
        },
        {
          "category": "external",
          "summary": "https://hackerone.com/reports/3467067",
          "url": "https://hackerone.com/reports/3467067"
        }
      ],
      "release_date": "2026-04-16T18:16:00Z",
      "threats": [
        {
          "category": "impact",
          "details": "Critical"
        },
        {
          "category": "impact",
          "date": "2026-10-15T17:53:21.983316Z",
          "details": "CVE-2026-27820 affects the Ruby zlib gem (ruby/zlib), a Ruby C-extension binding, which is not part of the zlib package for Debian 10 ELS; the package ships the C zlib compression library and does not contain the vulnerable Zlib::GzipReader code.",
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            "Debian-10:zlib1g-1:1.2.11.dfsg-1+deb10u2+tuxcare.els1.armel",
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            "Debian-10:zlib1g-dev-1:1.2.11.dfsg-1+deb10u2+tuxcare.els1.armel"
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}