{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-11721","assignerOrgId":"404fd4d2-a609-4245-b543-2c944a302a22","state":"PUBLISHED","assignerShortName":"isc","dateReserved":"2026-06-09T01:19:47.697Z","datePublished":"2026-07-22T14:13:08.748Z","dateUpdated":"2026-07-22T18:52:46.888Z"},"containers":{"cna":{"providerMetadata":{"orgId":"404fd4d2-a609-4245-b543-2c944a302a22","shortName":"isc","dateUpdated":"2026-07-22T14:13:08.748Z"},"title":"Cache poisoning possible with label count discrepancy, RRSIG, and wildcards","datePublic":"2026-07-22T00:00:00.000Z","affected":[{"vendor":"ISC","product":"BIND 9","versions":[{"version":"9.11.0","lessThanOrEqual":"9.18.50","status":"affected","versionType":"custom"},{"version":"9.20.0","lessThanOrEqual":"9.20.24","status":"affected","versionType":"custom"},{"version":"9.21.0","lessThanOrEqual":"9.21.23","status":"affected","versionType":"custom"},{"version":"9.11.3-S1","lessThanOrEqual":"9.18.50-S1","status":"affected","versionType":"custom"},{"version":"9.20.9-S1","lessThanOrEqual":"9.20.24-S1","status":"affected","versionType":"custom"}],"defaultStatus":"unaffected"}],"cpeApplicability":[{"nodes":[{"operator":"OR","cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*","versionStartIncluding":"9.11.0","versionEndIncluding":"9.18.50"},{"vulnerable":true,"criteria":"cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*","versionStartIncluding":"9.20.0","versionEndIncluding":"9.20.24"},{"vulnerable":true,"criteria":"cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*","versionStartIncluding":"9.21.0","versionEndIncluding":"9.21.23"},{"vulnerable":true,"criteria":"cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*","versionStartIncluding":"9.11.3-S1","versionEndIncluding":"9.18.50-S1"},{"vulnerable":true,"criteria":"cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*","versionStartIncluding":"9.20.9-S1","versionEndIncluding":"9.20.24-S1"}]}]}],"metrics":[{"cvssV3_1":{"version":"3.1","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"HIGH","availabilityImpact":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","baseScore":7.5,"baseSeverity":"HIGH"}}],"problemTypes":[{"descriptions":[{"lang":"en","type":"CWE","cweId":"CWE-1284","description":"CWE-1284 Improper Validation of Specified Quantity in Input"}]}],"descriptions":[{"lang":"en","value":"It is possible for an attacker's zone to respond to a query with an RRSIG that has a smaller number of labels than the zone in which the RRSIG is contained. This causes `named` to produce a wildcard name for a zone that is shorter than the attacker's zone, which can result in cache poisoning. For this attack to have any effect, the resolver under attack must have set `synth-from-dnssec yes;` (which is the default).\nThis issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.24, 9.21.0 through 9.21.23, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.24-S1."}],"impacts":[{"descriptions":[{"lang":"en","value":"Potential cache poisoning."}]}],"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: 9.20.26, 9.21.24, or 9.20.26-S1."}],"credits":[{"lang":"en","value":"ISC would like to thank Qifan Zhang of Palo Alto Networks for bringing this vulnerability to our attention."}],"references":[{"url":"https://kb.isc.org/docs/cve-2026-11721","name":"CVE-2026-11721","tags":["vendor-advisory"]},{"url":"https://downloads.isc.org/isc/bind9/9.20.26","tags":["patch"]},{"url":"https://downloads.isc.org/isc/bind9/9.21.24","tags":["patch"]}],"source":{"discovery":"EXTERNAL"},"x_generator":{"engine":"cvelib 1.8.0"}},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-07-22T18:52:35.390125Z","id":"CVE-2026-11721","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-07-22T18:52:46.888Z"}}]}}