A stack use-after-return flaw in SIG(0) handling code may enable ACL bypass_CVE-2026-3591

{
    "lastseen": "",
    "description": "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.",
    "published": "2026-03-25T13:34:14.202Z",
    "modified": "2026-03-25T14:13:01.659Z",
    "type": "cve",
    "title": "A stack use-after-return flaw in SIG(0) handling code may enable ACL bypass",
    "source": "isc",
    "references": "https://kb.isc.org/docs/cve-2026-3591\nhttps://downloads.isc.org/isc/bind9/9.20.21\nhttps://downloads.isc.org/isc/bind9/9.21.20",
    "id": "CVE-2026-3591",
    "bulletinFamily": "",
    "cwe": [
        "CWE-562",
        "CWE-305"
    ],
    "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": 5.4,
        "severity": "MEDIUM",
        "vector": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N",
        "version": "3.1"
    },
    "cvss2": [],
    "cvss3": {
        "version": "",
        "vectorString": "",
        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
            "vectorString": "",
            "baseScore": 0,
            "baseSeverity": "",
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            "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
}