{"id":"CVE-2026-11721","state":"PUBLISHED","title":"Cache poisoning possible with label count discrepancy, RRSIG, and wildcards","description":"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.","publishedAt":"2026-07-22T14:13:08.748Z","updatedAt":"2026-07-22T18:52:46.888Z","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:H/A:N","source":"isc"},"assigner":"isc","products":["ISC BIND 9"],"affected":[{"vendor":"ISC","product":"BIND 9","defaultStatus":"unaffected","versions":[{"version":"9.11.0","status":"affected","lessThanOrEqual":"9.18.50","versionType":"custom"},{"version":"9.20.0","status":"affected","lessThanOrEqual":"9.20.24","versionType":"custom"},{"version":"9.21.0","status":"affected","lessThanOrEqual":"9.21.23","versionType":"custom"},{"version":"9.11.3-S1","status":"affected","lessThanOrEqual":"9.18.50-S1","versionType":"custom"},{"version":"9.20.9-S1","status":"affected","lessThanOrEqual":"9.20.24-S1","versionType":"custom"}]}],"references":["https://kb.isc.org/docs/cve-2026-11721","https://downloads.isc.org/isc/bind9/9.20.26","https://downloads.isc.org/isc/bind9/9.21.24"],"weaknesses":["CWE-1284"],"ingestedAt":"2026-10-29T20:10:52.580Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/11xxx/CVE-2026-11721.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-11721","state":"PUBLISHED","datePublished":"2026-07-22T14:13:08.748Z","dateUpdated":"2026-07-22T18:52:46.888Z","assignerShortName":"isc","assignerOrgId":"404fd4d2-a609-4245-b543-2c944a302a22","dateReserved":"2026-06-09T01:19:47.697Z"},"containers":{"cna":{"title":"Cache poisoning possible with label count discrepancy, RRSIG, and wildcards","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."}],"affected":[{"vendor":"ISC","product":"BIND 9","defaultStatus":"unaffected","versions":[{"version":"9.11.0","status":"affected","lessThanOrEqual":"9.18.50","versionType":"custom"},{"version":"9.20.0","status":"affected","lessThanOrEqual":"9.20.24","versionType":"custom"},{"version":"9.21.0","status":"affected","lessThanOrEqual":"9.21.23","versionType":"custom"},{"version":"9.11.3-S1","status":"affected","lessThanOrEqual":"9.18.50-S1","versionType":"custom"},{"version":"9.20.9-S1","status":"affected","lessThanOrEqual":"9.20.24-S1","versionType":"custom"}]}],"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"]}],"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":[{"cweId":"CWE-1284","lang":"en","type":"CWE","description":"CWE-1284 Improper Validation of Specified Quantity in Input"}]}],"providerMetadata":{"shortName":"isc","orgId":"404fd4d2-a609-4245-b543-2c944a302a22","dateUpdated":"2026-07-22T14:13:08.748Z"},"datePublic":"2026-07-22T00:00:00.000Z","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"}]}]}],"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."}],"source":{"discovery":"EXTERNAL"},"x_generator":{"engine":"cvelib 1.8.0"}},"adp":[{"title":"CISA ADP Vulnrichment","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"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-07-22T18:52:46.888Z"}}]}}}