CVE-2026-81634

{"id": "CVE-2026-81634", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-81634", "role": "CISA Coordinator", "options": [{"exploitation": "none"}, {"automatable": "yes"}, {"technicalImpact": "partial"}], "version": "2.0.3", "timestamp": "2026-09-16T14:32:31.803030Z"}}], "cvssMetricV31": [{"type": "Secondary", "source": "sep@nlnetlabs.nl", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 7.5, "attackVector": "NETWORK", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "NONE", "confidentialityImpact": "NONE"}, "impactScore": 3.6, "exploitabilityScore": 3.9}]}, "affected": [{"source": "sep@nlnetlabs.nl", "affectedData": [{"vendor": "NLnet Labs", "product": "Unbound", "versions": [{"status": "affected", "version": "0", "lessThan": "1.26.1", "versionType": "semver"}], "defaultStatus": "unaffected"}]}], "published": "2026-09-16T09:17:06.210", "references": [{"url": "https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-81634.txt", "tags": ["Patch", "Vendor Advisory"], "source": "sep@nlnetlabs.nl"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Secondary", "source": "sep@nlnetlabs.nl", "description": [{"lang": "en", "value": "CWE-122"}]}], "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."}], "lastModified": "2026-09-23T19:51:14.940", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:nlnetlabs:unbound:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "EFE466C2-2830-48B5-AD1D-0138CB8207A7", "versionEndExcluding": "1.26.1"}], "operator": "OR"}]}], "sourceIdentifier": "sep@nlnetlabs.nl"}