{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-3591","assignerOrgId":"404fd4d2-a609-4245-b543-2c944a302a22","state":"PUBLISHED","assignerShortName":"isc","dateReserved":"2026-03-05T12:50:58.915Z","datePublished":"2026-03-25T13:34:14.202Z","dateUpdated":"2026-03-25T14:13:01.659Z"},"containers":{"cna":{"providerMetadata":{"orgId":"404fd4d2-a609-4245-b543-2c944a302a22","shortName":"isc","dateUpdated":"2026-03-25T13:34:14.202Z"},"title":"A stack use-after-return flaw in SIG(0) handling code may enable ACL bypass","datePublic":"2026-03-25T00:00:00.000Z","affected":[{"vendor":"ISC","product":"BIND 9","versions":[{"version":"9.20.0","lessThanOrEqual":"9.20.20","status":"affected","versionType":"custom"},{"version":"9.21.0","lessThanOrEqual":"9.21.19","status":"affected","versionType":"custom"},{"version":"9.20.9-S1","lessThanOrEqual":"9.20.20-S1","status":"affected","versionType":"custom"},{"version":"9.18.0","lessThanOrEqual":"9.18.46","status":"unaffected","versionType":"custom"},{"version":"9.18.11-S1","lessThanOrEqual":"9.18.46-S1","status":"unaffected","versionType":"custom"}],"defaultStatus":"unaffected"}],"cpeApplicability":[{"nodes":[{"operator":"OR","cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*","versionStartIncluding":"9.20.0","versionEndIncluding":"9.20.20"},{"vulnerable":true,"criteria":"cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*","versionStartIncluding":"9.21.0","versionEndIncluding":"9.21.19"},{"vulnerable":true,"criteria":"cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*","versionStartIncluding":"9.20.9-S1","versionEndIncluding":"9.20.20-S1"},{"vulnerable":false,"criteria":"cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*","versionStartIncluding":"9.18.0","versionEndIncluding":"9.18.46"},{"vulnerable":false,"criteria":"cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*","versionStartIncluding":"9.18.11-S1","versionEndIncluding":"9.18.46-S1"}]}]}],"metrics":[{"cvssV3_1":{"version":"3.1","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"LOW","integrityImpact":"LOW","availabilityImpact":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N","baseScore":5.4,"baseSeverity":"MEDIUM"}}],"problemTypes":[{"descriptions":[{"lang":"en","type":"CWE","cweId":"CWE-562","description":"CWE-562 Return of Stack Variable Address"},{"lang":"en","type":"CWE","cweId":"CWE-305","description":"CWE-305 Authentication Bypass by Primary Weakness"}]}],"descriptions":[{"lang":"en","value":"A use-after-return vulnerability exists in the `named` server when handling DNS queries signed with SIG(0). Using a specially-crafted DNS request, an attacker may be able to cause an ACL to improperly (mis)match an IP address. In a default-allow ACL (denying only specific IP addresses), this may lead to unauthorized access. Default-deny ACLs should fail-secure.\nThis issue affects BIND 9 versions 9.20.0 through 9.20.20, 9.21.0 through 9.21.19, and 9.20.9-S1 through 9.20.20-S1.\nBIND 9 versions 9.18.0 through 9.18.46 and 9.18.11-S1 through 9.18.46-S1 are NOT affected."}],"impacts":[{"descriptions":[{"lang":"en","value":"An attacker may be able to cause an ACL to improperly (mis)match an IP address.  In a default-allow ACL (denying only specific IP addresses), this may lead to unauthorized access."}]}],"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: 9.20.21, 9.21.20, or 9.20.21-S1."}],"credits":[{"lang":"en","value":"ISC would like to thank Mcsky23 for bringing this vulnerability to our attention."}],"references":[{"url":"https://kb.isc.org/docs/cve-2026-3591","name":"CVE-2026-3591","tags":["vendor-advisory"]},{"url":"https://downloads.isc.org/isc/bind9/9.20.21","tags":["patch"]},{"url":"https://downloads.isc.org/isc/bind9/9.21.20","tags":["patch"]}],"source":{"discovery":"EXTERNAL"},"x_generator":{"engine":"cvelib 1.8.0"}},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-03-25T14:12:43.295485Z","id":"CVE-2026-3591","options":[{"Exploitation":"none"},{"Automatable":"no"},{"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":"2026-03-25T14:13:01.659Z"}}]}}