{"id":"CVE-2026-5946","state":"PUBLISHED","title":"Invalid handling of CLASS != IN","description":"Multiple flaws have been identified in `named` related to the handling of DNS messages whose CLASS is not Internet (`IN`) — for example, `CHAOS` or `HESIOD`, or DNS messages that specify meta-classes (`ANY` or `NONE`) in the question section. Specially crafted requests reaching the affected code paths — recursion, dynamic updates (`UPDATE`), zone change notifications (`NOTIFY`), or processing of `IN`-specific record types in non-`IN` data — can cause assertion failures in `named`.\nThis issue affects BIND 9 versions 9.11.0 through 9.16.50, 9.18.0 through 9.18.48, 9.20.0 through 9.20.22, 9.21.0 through 9.21.21, 9.11.3-S1 through 9.16.50-S1, 9.18.11-S1 through 9.18.48-S1, and 9.20.9-S1 through 9.20.22-S1.","publishedAt":"2026-05-20T13:10:03.479Z","updatedAt":"2026-09-17T12:04:38.551Z","severity":{"score":7.5,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","source":"isc"},"assigner":"isc","products":["ISC BIND 9"],"affected":[{"vendor":"ISC","product":"BIND 9","defaultStatus":"unaffected","versions":[{"version":"9.11.0","status":"affected","lessThanOrEqual":"9.16.50","versionType":"custom"},{"version":"9.18.0","status":"affected","lessThanOrEqual":"9.18.48","versionType":"custom"},{"version":"9.20.0","status":"affected","lessThanOrEqual":"9.20.22","versionType":"custom"},{"version":"9.21.0","status":"affected","lessThanOrEqual":"9.21.21","versionType":"custom"},{"version":"9.11.3-S1","status":"affected","lessThanOrEqual":"9.16.50-S1","versionType":"custom"},{"version":"9.18.11-S1","status":"affected","lessThanOrEqual":"9.18.48-S1","versionType":"custom"},{"version":"9.20.9-S1","status":"affected","lessThanOrEqual":"9.20.22-S1","versionType":"custom"}]}],"references":["https://kb.isc.org/docs/cve-2026-5946","https://downloads.isc.org/isc/bind9/9.18.49","https://downloads.isc.org/isc/bind9/9.20.23","https://downloads.isc.org/isc/bind9/9.21.22","https://access.redhat.com/security/cve/CVE-2026-5946","https://bugzilla.redhat.com/show_bug.cgi?id=2479771","https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-5946.json","https://access.redhat.com/errata/RHSA-2026:60383","https://access.redhat.com/errata/RHSA-2026:62549","https://access.redhat.com/errata/RHSA-2026:65851","https://access.redhat.com/errata/RHSA-2026:24338","https://access.redhat.com/errata/RHSA-2026:24339","https://access.redhat.com/errata/RHSA-2026:23360","https://access.redhat.com/errata/RHSA-2026:57189","https://access.redhat.com/errata/RHSA-2026:55441","https://access.redhat.com/errata/RHSA-2026:24367","https://access.redhat.com/errata/RHSA-2026:24368","https://access.redhat.com/errata/RHSA-2026:20334"],"weaknesses":["CWE-20","CWE-125","CWE-617","CWE-754","CWE-843","CWE-1287"],"ingestedAt":"2026-10-29T20:12:32.778Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/5xxx/CVE-2026-5946.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-5946","state":"PUBLISHED","datePublished":"2026-05-20T13:10:03.479Z","dateUpdated":"2026-09-17T12:04:38.551Z","assignerShortName":"isc","assignerOrgId":"404fd4d2-a609-4245-b543-2c944a302a22","dateReserved":"2026-04-09T06:40:07.319Z"},"containers":{"cna":{"title":"Invalid handling of CLASS != IN","descriptions":[{"lang":"en","value":"Multiple flaws have been identified in `named` related to the handling of DNS messages whose CLASS is not Internet (`IN`) — for example, `CHAOS` or `HESIOD`, or DNS messages that specify meta-classes (`ANY` or `NONE`) in the question section. Specially crafted requests reaching the affected code paths — recursion, dynamic updates (`UPDATE`), zone change notifications (`NOTIFY`), or processing of `IN`-specific record types in non-`IN` data — can cause assertion failures in `named`.\nThis issue affects BIND 9 versions 9.11.0 through 9.16.50, 9.18.0 through 9.18.48, 9.20.0 through 9.20.22, 9.21.0 through 9.21.21, 9.11.3-S1 through 9.16.50-S1, 9.18.11-S1 through 9.18.48-S1, and 9.20.9-S1 through 9.20.22-S1."}],"affected":[{"vendor":"ISC","product":"BIND 9","defaultStatus":"unaffected","versions":[{"version":"9.11.0","status":"affected","lessThanOrEqual":"9.16.50","versionType":"custom"},{"version":"9.18.0","status":"affected","lessThanOrEqual":"9.18.48","versionType":"custom"},{"version":"9.20.0","status":"affected","lessThanOrEqual":"9.20.22","versionType":"custom"},{"version":"9.21.0","status":"affected","lessThanOrEqual":"9.21.21","versionType":"custom"},{"version":"9.11.3-S1","status":"affected","lessThanOrEqual":"9.16.50-S1","versionType":"custom"},{"version":"9.18.11-S1","status":"affected","lessThanOrEqual":"9.18.48-S1","versionType":"custom"},{"version":"9.20.9-S1","status":"affected","lessThanOrEqual":"9.20.22-S1","versionType":"custom"}]}],"references":[{"url":"https://kb.isc.org/docs/cve-2026-5946","name":"CVE-2026-5946","tags":["vendor-advisory"]},{"url":"https://downloads.isc.org/isc/bind9/9.18.49","tags":["patch"]},{"url":"https://downloads.isc.org/isc/bind9/9.20.23","tags":["patch"]},{"url":"https://downloads.isc.org/isc/bind9/9.21.22","tags":["patch"]}],"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":[{"cweId":"CWE-20","lang":"en","type":"CWE","description":"CWE-20 Improper Input Validation"},{"cweId":"CWE-125","lang":"en","type":"CWE","description":"CWE-125 Out-of-bounds Read"},{"cweId":"CWE-617","lang":"en","type":"CWE","description":"CWE-617 Reachable Assertion"},{"cweId":"CWE-754","lang":"en","type":"CWE","description":"CWE-754 Improper Check for Unusual or Exceptional Conditions"},{"cweId":"CWE-843","lang":"en","type":"CWE","description":"CWE-843 Access of Resource Using Incompatible Type ('Type Confusion')"}]}],"providerMetadata":{"shortName":"isc","orgId":"404fd4d2-a609-4245-b543-2c944a302a22","dateUpdated":"2026-05-20T13:10:03.479Z"},"datePublic":"2026-05-20T00:00:00.000Z","cpeApplicability":[{"nodes":[{"operator":"OR","cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*","versionStartIncluding":"9.11.0","versionEndIncluding":"9.16.50"},{"vulnerable":true,"criteria":"cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*","versionStartIncluding":"9.18.0","versionEndIncluding":"9.18.48"},{"vulnerable":true,"criteria":"cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*","versionStartIncluding":"9.20.0","versionEndIncluding":"9.20.22"},{"vulnerable":true,"criteria":"cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*","versionStartIncluding":"9.21.0","versionEndIncluding":"9.21.21"},{"vulnerable":true,"criteria":"cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*","versionStartIncluding":"9.11.3-S1","versionEndIncluding":"9.16.50-S1"},{"vulnerable":true,"criteria":"cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*","versionStartIncluding":"9.18.11-S1","versionEndIncluding":"9.18.48-S1"},{"vulnerable":true,"criteria":"cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*","versionStartIncluding":"9.20.9-S1","versionEndIncluding":"9.20.22-S1"}]}]}],"impacts":[{"descriptions":[{"lang":"en","value":"An attacker able to send specially crafted DNS messages to an affected `named` instance can cause it to terminate unexpectedly, resulting in a denial of service."}]}],"workarounds":[{"lang":"en","value":"Don't configure zones other than Internet (`IN`) class. Furthermore, do not expose the server that allows DNS Dynamic Update to the general Internet."}],"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: 9.18.49, 9.20.23, 9.21.22, 9.18.49-S1, or 9.20.23-S1."}],"credits":[{"lang":"en","value":"ISC would like to thank Mcsky23 for bringing this vulnerability to our attention."}],"source":{"discovery":"EXTERNAL"},"x_generator":{"engine":"cvelib 1.8.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-05-20T13:40:04.619504Z","id":"CVE-2026-5946","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-05-20T13:40:20.966Z"}},{"title":"bind: BIND: Denial of Service via specially crafted DNS messages","descriptions":[{"lang":"en","value":"A flaw was found in the bind component, specifically within the `named` daemon. This vulnerability allows a remote attacker to send specially crafted Domain Name System (DNS) messages. These messages, which use unusual classes or meta-classes, can trigger assertion failures in the `named` daemon when processed. 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