{
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      "text": "Medium"
    },
    "category": "csaf_vex",
    "csaf_version": "2.0",
    "distribution": {
      "text": "TuxCare License Agreement",
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        "label": "WHITE",
        "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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        "url": "https://security.tuxcare.com/csaf/v2/els_os/centos7els/vex/2026/cve-2026-4893-els_os-centos7els.json"
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      "generator": {
        "date": "2026-05-18T18:24:40Z",
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      "revision_history": [
        {
          "date": "2026-05-09T00:00:00Z",
          "number": "1",
          "summary": "Initial version"
        },
        {
          "date": "2026-05-18T14:17:43Z",
          "number": "2",
          "summary": "Official Publication"
        },
        {
          "date": "2026-05-18T18:24:40Z",
          "number": "3",
          "summary": "Update document"
        }
      ],
      "status": "final",
      "version": "3"
    },
    "title": "Security update on CVE-2026-4893"
  },
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  "vulnerabilities": [
    {
      "cve": "CVE-2026-4893",
      "cwe": {
        "id": "CWE-20",
        "name": "Improper Input Validation"
      },
      "notes": [
        {
          "category": "description",
          "text": "A validation bypass was discovered in dnsmasq's RFC 7871 client subnet (ECS) handling. When verifying ECS source information in DNS responses, dnsmasq passes the OPT record length instead of the full packet length to the validation function.This causes all internal bounds checks to fail, completely bypassing ECS source validation and allowing an attacker to spoof client subnet information.",
          "title": "Vulnerability description"
        },
        {
          "category": "general",
          "text": "The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.",
          "title": "CVSS score applicability"
        }
      ],
      "product_status": {
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          "CentOS-7:dnsmasq-0:2.76-17.el7_9.3.tuxcare.els3.x86_64",
          "CentOS-7:dnsmasq-0:2.76-17.el7_9.3.x86_64",
          "CentOS-7:dnsmasq-utils-0:2.76-17.el7_9.3.tuxcare.els1.x86_64",
          "CentOS-7:dnsmasq-utils-0:2.76-17.el7_9.3.tuxcare.els3.x86_64",
          "CentOS-7:dnsmasq-utils-0:2.76-17.el7_9.3.x86_64"
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          "summary": "Canonical URL",
          "url": "https://cve.tuxcare.com/els/cve/CVE-2026-4893"
        }
      ],
      "release_date": "2026-05-09T00:00:00Z",
      "remediations": [
        {
          "category": "no_fix_planned",
          "date": "2026-05-18T17:15:48.698501Z",
          "details": "This flaw only applies when dnsmasq is explicitly configured to use EDNS Client Subnet (ECS) via non-default options (for example, --add-subnet); with ECS disabled by default, the vulnerable validation path is not exercised in standard deployments. Even when ECS is enabled, the issue only permits spoofing of the ECS hint (affecting CDN/geolocation choices) and does not enable arbitrary DNS cache poisoning, bypass DNSSEC validation, escalate privilege, or impact availability. Given the prerequisite non-default configuration and the impact being limited to low-sensitivity metadata rather than DNS answer integrity or service continuity, this CVE can be safely deprioritized.",
          "product_ids": [
            "CentOS-7:dnsmasq-0:2.76-17.el7_9.3.tuxcare.els1.x86_64",
            "CentOS-7:dnsmasq-0:2.76-17.el7_9.3.tuxcare.els3.x86_64",
            "CentOS-7:dnsmasq-0:2.76-17.el7_9.3.x86_64",
            "CentOS-7:dnsmasq-utils-0:2.76-17.el7_9.3.tuxcare.els1.x86_64",
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        }
      ],
      "scores": [
        {
          "cvss_v3": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 6.5,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "LOW",
            "integrityImpact": "LOW",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N",
            "version": "3.1"
          },
          "products": [
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      ],
      "threats": [
        {
          "category": "impact",
          "details": "Moderate"
        }
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    }
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}