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CVE-2026-81736 (GCVE-0-2026-81736)

Vulnerability from cvelistv5 – Published: 2026-09-16 13:44 – Updated: 2026-09-16 13:44
VLAI
Title
Remote CPU denial of service through cached SVCB/HTTPS AliasMode trees
Summary
If a BIND resolver has cached a tree of SVCB/HTTPS AliasMode records, and is then queried for the root of that tree, the resolver will spend disproportionate CPU time constructing the response. This issue affects BIND 9 versions 9.18.0 through 9.18.50, 9.20.0 through 9.20.27, 9.21.0 through 9.21.25, 9.18.11-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.27-S1.
Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CWE
  • CWE-1050 - Excessive Platform Resource Consumption within a Loop
Assigner
References
Impacted products
Vendor Product Version CPE status
ISC BIND 9 Affected: 9.18.0 , ≤ 9.18.50 (custom)
Affected: 9.20.0 , ≤ 9.20.27 (custom)
Affected: 9.21.0 , ≤ 9.21.25 (custom)
Affected: 9.18.11-S1 , ≤ 9.18.50-S1 (custom)
Affected: 9.20.9-S1 , ≤ 9.20.27-S1 (custom)
    cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*
    cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*
    cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*
    cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*
    cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*
Create a notification for this product.
Date Public
2026-09-16 00:00
Credits
ISC would like to thank Henrique Pereira for bringing this vulnerability to our attention.
Show details on NVD website
To clipboard 

{
  "containers": {
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          "product": "BIND 9",
          "vendor": "ISC",
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              "status": "affected",
              "version": "9.20.0",
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              "version": "9.21.0",
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              "lessThanOrEqual": "9.18.50-S1",
              "status": "affected",
              "version": "9.18.11-S1",
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              "status": "affected",
              "version": "9.20.9-S1",
              "versionType": "custom"
            }
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      ],
      "cpeApplicability": [
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          "nodes": [
            {
              "cpeMatch": [
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                  "criteria": "cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*",
                  "versionEndIncluding": "9.18.50",
                  "versionStartIncluding": "9.18.0",
                  "vulnerable": true
                },
                {
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          "value": "ISC would like to thank Henrique Pereira for bringing this vulnerability to our attention."
        }
      ],
      "datePublic": "2026-09-16T00:00:00.000Z",
      "descriptions": [
        {
          "lang": "en",
          "value": "If a BIND resolver has cached a tree of SVCB/HTTPS AliasMode records, and is then queried for the root of that tree, the resolver will spend disproportionate CPU time constructing the response.\nThis issue affects BIND 9 versions 9.18.0 through 9.18.50, 9.20.0 through 9.20.27, 9.21.0 through 9.21.25, 9.18.11-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.27-S1."
        }
      ],
      "exploits": [
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          "lang": "en",
          "value": "We are not aware of any active exploits."
        }
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      "impacts": [
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          "descriptions": [
            {
              "lang": "en",
              "value": "A successful attack may result in resource exhaustion and a denial-of-service."
            }
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      ],
      "metrics": [
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          "cvssV3_1": {
            "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"
          }
        }
      ],
      "problemTypes": [
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          "descriptions": [
            {
              "cweId": "CWE-1050",
              "description": "CWE-1050 Excessive Platform Resource Consumption within a Loop",
              "lang": "en",
              "type": "CWE"
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      "providerMetadata": {
        "dateUpdated": "2026-09-16T13:44:28.052Z",
        "orgId": "404fd4d2-a609-4245-b543-2c944a302a22",
        "shortName": "isc"
      },
      "references": [
        {
          "name": "CVE-2026-81736",
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://kb.isc.org/docs/cve-2026-81736"
        },
        {
          "tags": [
            "patch"
          ],
          "url": "https://downloads.isc.org/isc/bind9/9.20.29"
        },
        {
          "tags": [
            "patch"
          ],
          "url": "https://downloads.isc.org/isc/bind9/9.21.26"
        }
      ],
      "solutions": [
        {
          "lang": "en",
          "value": "Upgrade to the patched release most closely related to your current version of BIND 9: 9.20.29, 9.21.26, or 9.20.29-S1."
        }
      ],
      "source": {
        "discovery": "EXTERNAL"
      },
      "title": "Remote CPU denial of service through cached SVCB/HTTPS AliasMode trees",
      "workarounds": [
        {
          "lang": "en",
          "value": "No workarounds known."
        }
      ],
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        "engine": "cvelib 1.8.0"
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    "cveId": "CVE-2026-81736",
    "datePublished": "2026-09-16T13:44:28.052Z",
    "dateReserved": "2026-08-27T11:35:23.313Z",
    "dateUpdated": "2026-09-16T13:44:28.052Z",
    "state": "PUBLISHED"
  },
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  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
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      "date": "2026-09-17",
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      "percentile": "0.40779"
    },
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    "redhat_vex": {
      "aggregate_severity": "Important",
      "current_release_date": "2026-09-17T11:23:21+00:00",
      "cve": "CVE-2026-81736",
      "id": "CVE-2026-81736",
      "initial_release_date": "2026-09-16T13:44:28.052000+00:00",
      "product_status:known_affected": "18",
      "product_status:known_not_affected": "70",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "bind: BIND 9: Remote Denial of Service via cached SVCB/HTTPS AliasMode records",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-81736.json",
      "version": "3"
    }
  }
}



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