Possible arbitrary code execution during DNSSEC validation_CVE-2026-33278

{
    "lastseen": "",
    "description": "NLnet Labs Unbound 1.19.1 up to and including version 1.25.0 has a vulnerability in the DNSSEC validator that enables denial of service and possible remote code execution as a result of deep copying a data structure and erroneously overwriting a destination pointer. An adversary can exploit the vulnerability by controlling a malicious signed zone and querying a vulnerable Unbound. When DS sub-queries need to suspend validation due to NSEC3 computational budget exhaustion (introduced in Unbound 1.19.1), Unbound deep-copies response messages to preserve them across memory region teardown. A struct-assignment bug overwrites the destination's pointer with the source's pointer. After the sub-query region is freed, the resumed validator dereferences this dangling pointer, triggering a crash or potentially enabling arbitrary code execution. Unbound 1.25.1 contains a patch with a fix to preserve the correct pointer when deep copying the data structure.",
    "published": "2026-05-20T09:18:15.225Z",
    "modified": "2026-05-20T09:18:15.225Z",
    "type": "cve",
    "title": "Possible arbitrary code execution during DNSSEC validation",
    "source": "NLnet Labs",
    "references": "https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-33278.txt",
    "id": "CVE-2026-33278",
    "bulletinFamily": "",
    "cwe": [
        "CWE-416",
        "CWE-672"
    ],
    "cvelist": null,
    "sourceData": "NLnet Labs Unbound 1.19.1",
    "sourceHref": "",
    "cvss": {
        "score": 9.1,
        "severity": "CRITICAL",
        "vector": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:U/U:Red",
        "version": "4.0"
    },
    "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": "Unbound",
    "version": "1.19.1",
    "vendor": "NLnet Labs",
    "ai_description": "Possible arbitrary code execution during DNSSEC validation due to a struct-assignment bug in Unbound's DNSSEC validator",
    "ai_severity": "Critical",
    "ai_vendor": "NLnet Labs",
    "ai_product": "Unbound",
    "ai_version": "1.19.1-1.25.0",
    "ai_score": 9.1
}