{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-40777","assignerOrgId":"404fd4d2-a609-4245-b543-2c944a302a22","state":"PUBLISHED","assignerShortName":"isc","dateReserved":"2025-04-16T08:44:49.856Z","datePublished":"2025-07-16T17:38:06.370Z","dateUpdated":"2025-11-04T21:10:12.751Z"},"containers":{"cna":{"providerMetadata":{"orgId":"404fd4d2-a609-4245-b543-2c944a302a22","shortName":"isc","dateUpdated":"2025-07-16T17:38:06.370Z"},"title":"A possible assertion failure when 'stale-answer-client-timeout' is set to '0'","datePublic":"2025-07-16T00:00:00.000Z","affected":[{"vendor":"ISC","product":"BIND 9","versions":[{"version":"9.20.0","lessThanOrEqual":"9.20.10","status":"affected","versionType":"custom"},{"version":"9.21.0","lessThanOrEqual":"9.21.9","status":"affected","versionType":"custom"},{"version":"9.20.9-S1","lessThanOrEqual":"9.20.10-S1","status":"affected","versionType":"custom"},{"version":"9.18.0","lessThanOrEqual":"9.18.37","status":"unaffected","versionType":"custom"},{"version":"9.18.11-S1","lessThanOrEqual":"9.18.37-S1","status":"unaffected","versionType":"custom"}],"defaultStatus":"unaffected"}],"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-617","description":"CWE-617 Reachable Assertion"}]}],"descriptions":[{"lang":"en","value":"If a `named` caching resolver is configured with `serve-stale-enable` `yes`, and with `stale-answer-client-timeout` set to `0` (the only allowable value other than `disabled`), and if the resolver, in the process of resolving a query, encounters a CNAME chain involving a specific combination of cached or authoritative records, the daemon will abort with an assertion failure.\nThis issue affects BIND 9 versions 9.20.0 through 9.20.10, 9.21.0 through 9.21.9, and 9.20.9-S1 through 9.20.10-S1."}],"impacts":[{"descriptions":[{"lang":"en","value":"If an attacker is able to make queries that yield the necessary combination of circumstances, they can force `named` to exit."}]}],"workarounds":[{"lang":"en","value":"Setting either of `stale-answer-client-timeout off;` or `stale-answer-enable no;` in the configuration file will prevent the assertion."}],"exploits":[{"lang":"en","value":"This flaw was discovered in internal testing. 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: 9.20.11, 9.21.10, or 9.20.11-S1."}],"references":[{"url":"https://kb.isc.org/docs/cve-2025-40777","name":"CVE-2025-40777","tags":["vendor-advisory"]}],"source":{"discovery":"INTERNAL"}},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2025-07-18T14:25:41.033326Z","id":"CVE-2025-40777","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":"2025-07-18T14:25:48.883Z"}},{"title":"CVE Program Container","references":[{"url":"http://www.openwall.com/lists/oss-security/2025/07/16/6"}],"providerMetadata":{"orgId":"af854a3a-2127-422b-91ae-364da2661108","shortName":"CVE","dateUpdated":"2025-11-04T21:10:12.751Z"}}]}}