{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-5947","assignerOrgId":"404fd4d2-a609-4245-b543-2c944a302a22","state":"PUBLISHED","assignerShortName":"isc","dateReserved":"2026-04-09T06:40:58.672Z","datePublished":"2026-05-20T13:10:11.873Z","dateUpdated":"2026-06-30T12:11:11.730Z"},"containers":{"cna":{"providerMetadata":{"orgId":"404fd4d2-a609-4245-b543-2c944a302a22","shortName":"isc","dateUpdated":"2026-05-20T13:10:11.873Z"},"title":"SIG(0) validation during query flood may lead to undefined behavior","datePublic":"2026-05-20T00:00:00.000Z","affected":[{"vendor":"ISC","product":"BIND 9","versions":[{"version":"9.20.0","lessThanOrEqual":"9.20.22","status":"affected","versionType":"custom"},{"version":"9.21.0","lessThanOrEqual":"9.21.21","status":"affected","versionType":"custom"},{"version":"9.20.9-S1","lessThanOrEqual":"9.20.22-S1","status":"affected","versionType":"custom"},{"version":"9.18.28","lessThanOrEqual":"9.18.49","status":"unaffected","versionType":"custom"},{"version":"9.18.28-S1","lessThanOrEqual":"9.18.49-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":"9.20.22"},{"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":"9.20.9-S1","versionEndIncluding":"9.20.22-S1"},{"vulnerable":false,"criteria":"cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*","versionStartIncluding":"9.18.28","versionEndIncluding":"9.18.49"},{"vulnerable":false,"criteria":"cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*","versionStartIncluding":"9.18.28-S1","versionEndIncluding":"9.18.49-S1"}]}]}],"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":[{"lang":"en","type":"CWE","cweId":"CWE-362","description":"CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')"},{"lang":"en","type":"CWE","cweId":"CWE-416","description":"CWE-416 Use After Free"}]}],"descriptions":[{"lang":"en","value":"Undefined behavior may result due to a race condition leading to a use-after-free violation.  If BIND receives an incoming DNS message signed with SIG(0), it begins work to validate that signature.  If, during that validation, the \"recursive-clients\" limit is reached (as would occur during a query flood), and that same DNS message is discarded per the limit, there is a brief window of time while the SIG(0) validation may attempt to read the now-discarded DNS message.\nThis issue affects BIND 9 versions 9.20.0 through 9.20.22, 9.21.0 through 9.21.21, and 9.20.9-S1 through 9.20.22-S1.\nBIND 9 versions 9.18.28 through 9.18.49 and 9.18.28-S1 through 9.18.49-S1 are NOT affected."}],"impacts":[{"descriptions":[{"lang":"en","value":"The use of memory after it is freed is undefined (\"dangling pointer\").  The BIND process may abort with a segmentation violation or similar error.  If memory from the discarded message has not been reused or reclaimed, the validation might proceed normally.  Any kind of code execution from such an improper data read is unlikely."}]}],"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: 9.20.23, 9.21.22, or 9.20.23-S1."}],"credits":[{"lang":"en","value":"ISC would like to thank Naoki Wakamatsu for bringing this vulnerability to our attention."}],"references":[{"url":"https://kb.isc.org/docs/cve-2026-5947","name":"CVE-2026-5947","tags":["vendor-advisory"]},{"url":"https://downloads.isc.org/isc/bind9/9.20.23","tags":["patch"]},{"url":"https://downloads.isc.org/isc/bind9/9.21.22","tags":["patch"]}],"source":{"discovery":"EXTERNAL"},"x_generator":{"engine":"cvelib 1.8.0"}},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-05-20T13:39:15.454199Z","id":"CVE-2026-5947","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":"2026-05-20T13:39:38.654Z"}},{"affected":[{"cpes":["cpe:/a:redhat:hummingbird:1"],"defaultStatus":"affected","product":"Red Hat Hardened Images","vendor":"Red Hat"},{"cpes":["cpe:/o:redhat:enterprise_linux:10"],"defaultStatus":"unaffected","product":"Red Hat Enterprise Linux 10","vendor":"Red Hat"},{"cpes":["cpe:/o:redhat:enterprise_linux:6"],"defaultStatus":"unaffected","product":"Red Hat Enterprise Linux 6","vendor":"Red Hat"},{"cpes":["cpe:/o:redhat:enterprise_linux:7"],"defaultStatus":"unaffected","product":"Red Hat Enterprise Linux 7","vendor":"Red Hat"},{"cpes":["cpe:/o:redhat:enterprise_linux:8"],"defaultStatus":"unaffected","product":"Red Hat Enterprise Linux 8","vendor":"Red Hat"},{"cpes":["cpe:/o:redhat:enterprise_linux:9"],"defaultStatus":"unaffected","product":"Red Hat Enterprise Linux 9","vendor":"Red Hat"},{"cpes":["cpe:/a:redhat:openshift:4"],"defaultStatus":"unaffected","product":"Red Hat OpenShift Container Platform 4","vendor":"Red Hat"}],"datePublic":"2026-05-21T12:15:50.513Z","descriptions":[{"lang":"en","value":"A flaw was found in BIND. A remote attacker could exploit a race condition during SIG(0) signature validation of an incoming DNS message. If the \"recursive-clients\" limit is reached and the message is discarded, a use-after-free vulnerability may occur. This could lead to undefined behavior and potentially result in a denial of service."}],"metrics":[{"other":{"content":{"namespace":"https://access.redhat.com/security/updates/classification/","value":"Important"},"type":"Red Hat severity rating"}},{"cvssV3_1":{"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"},"format":"CVSS"}],"problemTypes":[{"descriptions":[{"cweId":"CWE-367","description":"Time-of-check Time-of-use (TOCTOU) Race Condition","lang":"en","type":"CWE"}]}],"references":[{"tags":["vdb-entry","x_refsource_REDHAT"],"url":"https://access.redhat.com/security/cve/CVE-2026-5947"},{"name":"RHBZ#2479772","tags":["issue-tracking","x_refsource_REDHAT"],"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2479772"},{"tags":["x_sadp-csaf-vex"],"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-5947.json"},{"tags":["vendor-advisory","x_refsource_REDHAT"],"url":"https://access.redhat.com/errata/RHSA-2026:7412"}],"solutions":[{"lang":"en","value":"RHSA-2026:7412: Red Hat Hardened Images"}],"timeline":[{"lang":"en","time":"2026-05-19T09:59:51.277Z","value":"Reported to Red Hat."},{"lang":"en","time":"2026-05-21T12:15:50.513Z","value":"Made public."}],"title":"bind: SIG(0) validation during query flood may lead to undefined behavior","workarounds":[{"lang":"en","value":"Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability."}],"x_adpType":"supplier","x_generator":{"engine":"sadp-cli 1.0.0"},"providerMetadata":{"orgId":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c","shortName":"redhat-SADP","dateUpdated":"2026-06-30T12:11:11.730Z"}}]}}