{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-81634",
        "assignerOrgId": "206fc3a0-e175-490b-9eaa-a5738056c9f6",
        "state": "PUBLISHED",
        "assignerShortName": "NLnet Labs",
        "dateReserved": "2026-09-07T14:06:21.967Z",
        "datePublished": "2026-09-16T08:30:15.428Z",
        "dateUpdated": "2026-09-16T14:32:38.842Z"
    },
    "containers": {
        "cna": {
            "title": "Possible heap buffer overflow during DNSSEC canonicalization",
            "datePublic": "2026-09-16T00:00:00.000Z",
            "affected": [
                {
                    "vendor": "NLnet Labs",
                    "product": "Unbound",
                    "versions": [
                        {
                            "version": "0",
                            "status": "affected",
                            "lessThan": "1.26.1",
                            "versionType": "semver"
                        }
                    ],
                    "defaultStatus": "unaffected"
                }
            ],
            "descriptions": [
                {
                    "lang": "en",
                    "value": "In NLnet Labs Unbound up to and including 1.26.0, a 255 length query name with a large TCP response can lead to a heap buffer overflow during the RRSet canonicalisation routine. This is caused by missing to add the first owner name into the buffer length check. A malicious actor operating a malicious name server or tampering with an incoming response to Unbound (canonicalisation happens before DNSSEC validation), can trigger the vulnerability."
                }
            ],
            "metrics": [
                {
                    "format": "CVSS",
                    "scenarios": [
                        {
                            "lang": "en",
                            "value": "GENERAL"
                        }
                    ],
                    "cvssV3_1": {
                        "version": "3.1",
                        "baseScore": 7.5,
                        "baseSeverity": "HIGH",
                        "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
                    }
                }
            ],
            "problemTypes": [
                {
                    "descriptions": [
                        {
                            "lang": "en",
                            "cweId": "CWE-122",
                            "description": "CWE-122: Heap-based Buffer Overflow",
                            "type": "CWE"
                        }
                    ]
                }
            ],
            "solutions": [
                {
                    "lang": "en",
                    "value": "This issue is fixed starting with version 1.26.1"
                }
            ],
            "timeline": [
                {
                    "time": "2026-07-31T00:00:00.000Z",
                    "lang": "en",
                    "value": "Issue reported by Vlatko Kosturjak"
                },
                {
                    "time": "2026-08-03T00:00:00.000Z",
                    "lang": "en",
                    "value": "NLnet Labs shares patch"
                },
                {
                    "time": "2026-08-04T00:00:00.000Z",
                    "lang": "en",
                    "value": "Vlatko Kosturjak verifies patch"
                },
                {
                    "time": "2026-09-16T00:00:00.000Z",
                    "lang": "en",
                    "value": "Fixes released with version 1.26.1"
                }
            ],
            "credits": [
                {
                    "lang": "en",
                    "value": "Vlatko Kosturjak (Marlink Cyber)",
                    "type": "finder"
                }
            ],
            "references": [
                {
                    "url": "https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-81634.txt",
                    "tags": [
                        "vendor-advisory"
                    ]
                }
            ],
            "providerMetadata": {
                "orgId": "206fc3a0-e175-490b-9eaa-a5738056c9f6",
                "shortName": "NLnet Labs",
                "dateUpdated": "2026-09-16T08:30:15.428Z"
            },
            "x_generator": {
                "engine": "cvelib 1.8.0"
            }
        },
        "adp": [
            {
                "metrics": [
                    {
                        "other": {
                            "type": "ssvc",
                            "content": {
                                "timestamp": "2026-09-16T14:32:31.803030Z",
                                "id": "CVE-2026-81634",
                                "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": "2026-09-16T14:32:38.842Z"
                }
            }
        ]
    }
}