CVE-2026-81736

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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."}, {"lang": "es", "value": "Si un resolvedor BIND tiene en cach\u00e9 un \u00e1rbol de registros SVCB/HTTPS AliasMode y luego se le consulta por la ra\u00edz de ese \u00e1rbol, el resolvedor gastar\u00e1 un tiempo de CPU desproporcionado construyendo la respuesta. \\nEste problema afecta a BIND?9 desde la versi\u00f3n?9.18.0 hasta la versi\u00f3n?9.18.50 incluida, desde la versi\u00f3n?9.20.0 hasta la versi\u00f3n?9.20.27 incluida, desde la versi\u00f3n?9.21.0 hasta la versi\u00f3n?9.21.25 incluida, desde la versi\u00f3n?9.18.11?S1 hasta la versi\u00f3n?9.18.50?S1 incluida, y desde la versi\u00f3n?9.20.9?S1 hasta la versi\u00f3n?9.20.27?S1 incluida."}], "id": "CVE-2026-81736", "lastModified": "2026-10-26T21:10:00.170", "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": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-81736", "options": [{"exploitation": "none"}, {"automatable": "yes"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-09-17T18:45:52.174550Z", "version": "2.0.3"}}]}, "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": "Awaiting Analysis", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-1050"}], "source": "security-officer@isc.org", "type": "Secondary"}]}

{"bugzilla": {"description": "bind: BIND 9: Remote Denial of Service via cached SVCB/HTTPS AliasMode records", "id": "2535432", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2535432"}, "csaw": false, "cvss3": {"cvss3_base_score": "7.5", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-606", "details": ["A flaw was found in BIND 9. A remote attacker can exploit this vulnerability by querying a BIND resolver for the root of a specially crafted, cached tree of SVCB/HTTPS AliasMode records. This action causes the resolver to spend a disproportionate amount of CPU time constructing the response, leading to a denial of service (DoS) condition. This can make the affected BIND 9 resolver unresponsive to legitimate requests."], "mitigation": {"lang": "en:us", "value": "To mitigate the risk of this denial of service, configure BIND resolvers to restrict recursive queries to trusted clients only. This can be achieved by setting the `allow-recursion` option in the `named.conf` configuration file to specific IP addresses or networks. After modifying the configuration, the `named` service must be reloaded for the changes to take effect, which may temporarily interrupt DNS resolution."}, "name": "CVE-2026-81736", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Affected", "package_name": "bind", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Not affected", "package_name": "bind", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "bind", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "bind", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "bind9.16", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "bind", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "bind9.18", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "dhcp", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/a:redhat:hummingbird:1", "fix_state": "Affected", "package_name": "bind", "product_name": "Red Hat Hardened Images"}, {"cpe": "cpe:/a:redhat:openshift:4", "fix_state": "Affected", "package_name": "openshift/ose-rhel-coreos-8", "product_name": "Red Hat OpenShift Container Platform 4"}, {"cpe": "cpe:/a:redhat:openshift:4", "fix_state": "Affected", "package_name": "openshift/ose-rhel-coreos-9", "product_name": "Red Hat OpenShift Container Platform 4"}], "public_date": "2026-09-16T13:44:28Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-81736\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-81736\nhttps://downloads.isc.org/isc/bind9/9.20.29\nhttps://downloads.isc.org/isc/bind9/9.21.26\nhttps://kb.isc.org/docs/cve-2026-81736"], "statement": "This is an Important denial of service vulnerability in BIND 9 resolvers. An attacker can remotely trigger excessive CPU consumption by querying a resolver that has cached a specific tree of SVCB/HTTPS AliasMode records. This can lead to service disruption, particularly for resolvers exposed to untrusted networks.", "threat_severity": "Important"}

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