A possible assertion failure when ‘stale-answer-client-timeout’ is set to ‘0’_CVE-2025-40777

{
    "lastseen": "",
    "description": "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.",
    "published": "2025-07-16T17:38:06.370Z",
    "modified": "2025-07-18T14:25:48.883Z",
    "type": "cve",
    "title": "A possible assertion failure when 'stale-answer-client-timeout' is set to '0'",
    "source": "isc",
    "references": "https://kb.isc.org/docs/cve-2025-40777",
    "id": "CVE-2025-40777",
    "bulletinFamily": "",
    "cwe": [
        "CWE-617"
    ],
    "cvelist": null,
    "sourceData": "ISC BIND 9 9.20.0\nISC BIND 9 9.21.0\nISC BIND 9 9.20.9-S1",
    "sourceHref": "",
    "cvss": {
        "score": 7.5,
        "severity": "HIGH",
        "vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
        "version": "3.1"
    },
    "cvss2": [],
    "cvss3": {
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        "vectorString": "",
        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
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            "baseScore": 0,
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        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "BIND 9",
    "version": "9.20.0",
    "vendor": "ISC",
    "ai_description": "",
    "ai_severity": "",
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    "ai_score": 0
}