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        "cveId": "CVE-2026-44687",
        "assignerOrgId": "206fc3a0-e175-490b-9eaa-a5738056c9f6",
        "state": "PUBLISHED",
        "assignerShortName": "NLnet Labs",
        "dateReserved": "2026-06-22T12:35:21.340Z",
        "datePublished": "2026-07-22T13:06:42.751Z",
        "dateUpdated": "2026-07-22T14:19:53.266Z"
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        "cna": {
            "title": "Off-by-one error in 'harden-below-nxdomain' logic can shadow a stub/forward zone by a legitimate parent's NXDOMAIN",
            "datePublic": "2026-07-22T00:00:00.000Z",
            "affected": [
                {
                    "vendor": "NLnet Labs",
                    "product": "Unbound",
                    "versions": [
                        {
                            "version": "1.13.2",
                            "status": "affected",
                            "lessThan": "1.25.2",
                            "versionType": "semver"
                        }
                    ],
                    "defaultStatus": "unaffected"
                }
            ],
            "descriptions": [
                {
                    "lang": "en",
                    "value": "In NLnet Labs Unbound 1.13.2 up to and including 1.25.1, stub or forward zones where the name is below an intermediate labed below a DNSSEC signed zone could be shadowed by the intermediate label's secure NXDOMAIN answer from the parent. This is caused by an off-by-one error in 'harden-below-nxdomain' logic; enabled by default. It effectively bypasses the configuration and the configured stub/forward zone is never contacted. 'harden-below-nxdomain' does an upward DNS cache walk together with a delegation point guard that does not allow NXDOMAIN synthesis above stub/forward zones. The guard tests the domain name but before stripping a label. This results in an iteration where the domain name equals the configured stub/forward zone apex that passes the guard, strips one more label, and probes the cache at the apex's immediate public parent. If that parent has a cached DNSSEC-secure NXDOMAIN, which it will for any private namespace nested two or more labels under a signed public name, the walk returns it and the configured stub/forward upstream is never contacted. This can only be triggered by the query for the intermediate label (between the stub/forward apex and the DNSSEC parent zone)."
                }
            ],
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                        "version": "3.1",
                        "baseScore": 3.7,
                        "baseSeverity": "LOW",
                        "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L"
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            "problemTypes": [
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                    "descriptions": [
                        {
                            "lang": "en",
                            "cweId": "CWE-193",
                            "description": "CWE-193: Off-by-one Error",
                            "type": "CWE"
                        }
                    ]
                }
            ],
            "solutions": [
                {
                    "lang": "en",
                    "value": "This issue is fixed starting with version 1.25.2"
                }
            ],
            "timeline": [
                {
                    "time": "2026-05-04T00:00:00.000Z",
                    "lang": "en",
                    "value": "Issue reported by Qifan Zhang"
                },
                {
                    "time": "2026-05-29T00:00:00.000Z",
                    "lang": "en",
                    "value": "NLnet Labs shares patch"
                },
                {
                    "time": "2026-05-30T00:00:00.000Z",
                    "lang": "en",
                    "value": "Qifan Zhang verifies patch"
                },
                {
                    "time": "2026-07-22T00:00:00.000Z",
                    "lang": "en",
                    "value": "Fixes released with version 1.25.2"
                }
            ],
            "credits": [
                {
                    "lang": "en",
                    "value": "Qifan Zhang (Palo Alto Networks)",
                    "type": "finder"
                }
            ],
            "references": [
                {
                    "url": "https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-44687.txt",
                    "tags": [
                        "vendor-advisory"
                    ]
                }
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                "shortName": "NLnet Labs",
                "dateUpdated": "2026-07-22T13:06:42.751Z"
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                                "timestamp": "2026-07-22T14:19:38.843549Z",
                                "id": "CVE-2026-44687",
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