{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-81736", "assignerOrgId": "404fd4d2-a609-4245-b543-2c944a302a22", "state": "PUBLISHED", "assignerShortName": "isc", "dateReserved": "2026-08-27T11:35:23.313Z", "datePublished": "2026-09-16T13:44:28.052Z", "dateUpdated": "2026-09-16T13:44:28.052Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "404fd4d2-a609-4245-b543-2c944a302a22", "shortName": "isc", "dateUpdated": "2026-09-16T13:44:28.052Z"}, "title": "Remote CPU denial of service through cached SVCB/HTTPS AliasMode trees", "datePublic": "2026-09-16T00:00:00.000Z", "affected": [{"vendor": "ISC", "product": "BIND 9", "versions": [{"version": "9.18.0", "lessThanOrEqual": "9.18.50", "status": "affected", "versionType": "custom"}, {"version": "9.20.0", "lessThanOrEqual": "9.20.27", "status": "affected", "versionType": "custom"}, {"version": "9.21.0", "lessThanOrEqual": "9.21.25", "status": "affected", "versionType": "custom"}, {"version": "9.18.11-S1", "lessThanOrEqual": "9.18.50-S1", "status": "affected", "versionType": "custom"}, {"version": "9.20.9-S1", "lessThanOrEqual": "9.20.27-S1", "status": "affected", "versionType": "custom"}], "defaultStatus": "unaffected"}], "cpeApplicability": [{"nodes": [{"operator": "OR", "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*", "versionStartIncluding": "9.18.0", "versionEndIncluding": "9.18.50"}, {"vulnerable": true, "criteria": "cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*", "versionStartIncluding": "9.20.0", "versionEndIncluding": "9.20.27"}, {"vulnerable": true, "criteria": "cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*", "versionStartIncluding": "9.21.0", "versionEndIncluding": "9.21.25"}, {"vulnerable": true, "criteria": "cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*", "versionStartIncluding": "9.18.11-S1", "versionEndIncluding": "9.18.50-S1"}, {"vulnerable": true, "criteria": "cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*", "versionStartIncluding": "9.20.9-S1", "versionEndIncluding": "9.20.27-S1"}]}]}], "metrics": [{"cvssV3_1": {"version": "3.1", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "baseScore": 7.5, "baseSeverity": "HIGH"}}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "cweId": "CWE-1050", "description": "CWE-1050 Excessive Platform Resource Consumption within a Loop"}]}], "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."}], "impacts": [{"descriptions": [{"lang": "en", "value": "A successful attack may result in resource exhaustion and a denial-of-service."}]}], "workarounds": [{"lang": "en", "value": "No workarounds known."}], "exploits": [{"lang": "en", "value": "We are not aware of any active exploits."}], "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."}], "credits": [{"lang": "en", "value": "ISC would like to thank Henrique Pereira for bringing this vulnerability to our attention."}], "references": [{"url": "https://kb.isc.org/docs/cve-2026-81736", "name": "CVE-2026-81736", "tags": ["vendor-advisory"]}, {"url": "https://downloads.isc.org/isc/bind9/9.20.29", "tags": ["patch"]}, {"url": "https://downloads.isc.org/isc/bind9/9.21.26", "tags": ["patch"]}], "source": {"discovery": "EXTERNAL"}, "x_generator": {"engine": "cvelib 1.8.0"}}}}

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{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "BIND 9", "vendor": "ISC", "versions": [{"lessThanOrEqual": "9.18.50", "status": "affected", "version": "9.18.0", "versionType": "custom"}, {"lessThanOrEqual": "9.20.27", "status": "affected", "version": "9.20.0", "versionType": "custom"}, {"lessThanOrEqual": "9.21.25", "status": "affected", "version": "9.21.0", "versionType": "custom"}, {"lessThanOrEqual": "9.18.50-S1", "status": "affected", "version": "9.18.11-S1", "versionType": "custom"}, {"lessThanOrEqual": "9.20.27-S1", "status": "affected", "version": "9.20.9-S1", "versionType": "custom"}]}], "source": "security-officer@isc.org"}], "cveTags": [], "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."}], "id": "CVE-2026-81736", "lastModified": "2026-09-16T14:17:10.817", "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"}, "exploitabilityScore": 3.9, "impactScore": 3.6, "source": "security-officer@isc.org", "type": "Primary"}]}, "published": "2026-09-16T14:17:10.817", "references": [{"source": "security-officer@isc.org", "url": "https://downloads.isc.org/isc/bind9/9.20.29"}, {"source": "security-officer@isc.org", "url": "https://downloads.isc.org/isc/bind9/9.21.26"}, {"source": "security-officer@isc.org", "url": "https://kb.isc.org/docs/cve-2026-81736"}], "sourceIdentifier": "security-officer@isc.org", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-1050"}], "source": "security-officer@isc.org", "type": "Secondary"}]}

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