SIG(0) validation during query flood may lead to undefined behavior_CVE-2026-5947

{
    "lastseen": "",
    "description": "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.",
    "published": "2026-05-20T13:10:11.873Z",
    "modified": "2026-05-20T13:10:11.873Z",
    "type": "cve",
    "title": "SIG(0) validation during query flood may lead to undefined behavior",
    "source": "isc",
    "references": "https://kb.isc.org/docs/cve-2026-5947\nhttps://downloads.isc.org/isc/bind9/9.20.23\nhttps://downloads.isc.org/isc/bind9/9.21.22",
    "id": "CVE-2026-5947",
    "bulletinFamily": "",
    "cwe": [
        "CWE-362",
        "CWE-416"
    ],
    "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": {
        "version": "",
        "vectorString": "",
        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
            "vectorString": "",
            "baseScore": 0,
            "baseSeverity": "",
            "attackVector": "",
            "attackComplexity": "",
            "privilegesRequired": "",
            "userInteraction": "",
            "scope": "",
            "confidentialityImpact": "",
            "integrityImpact": "",
            "availabilityImpact": ""
        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "BIND 9",
    "version": "9.20.0",
    "vendor": "ISC",
    "ai_description": "",
    "ai_severity": "",
    "ai_vendor": "",
    "ai_product": "",
    "ai_version": "",
    "ai_score": 0
}