{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-4891", "assignerOrgId": "37e5125f-f79b-445b-8fad-9564f167944b", "state": "PUBLISHED", "assignerShortName": "certcc", "dateReserved": "2026-03-26T13:07:05.406Z", "datePublished": "2026-05-11T16:47:33.202Z", "dateUpdated": "2026-05-20T14:08:50.799Z"}, "containers": {"cna": {"title": "CVE-2026-4891", "descriptions": [{"lang": "en", "value": "A heap-based out-of-bounds read vulnerability in the DNSSEC validation of dnsmasq allows remote attackers to cause a denial of service via a crafted DNS packet."}], "source": {"discovery": "UNKNOWN"}, "affected": [{"vendor": "dnsmasq", "product": "dnsmasq", "versions": [{"status": "affected", "version": "0", "lessThan": "2.92rel2", "versionType": "custom"}]}], "problemTypes": [{"descriptions": [{"lang": "en", "description": "CWE-125: Out-of-bounds Read"}]}], "references": [{"url": "https://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2026q2/018471.html"}, {"url": "https://www.kb.cert.org/vuls/id/471747"}, {"url": "https://thekelleys.org.uk/dnsmasq/CVE/"}, {"url": "https://github.com/NixOS/nixpkgs/pull/519082"}, {"url": "https://github.com/NixOS/nixpkgs/pull/519093"}, {"url": "https://github.com/pi-hole/FTL/releases/tag/v6.6.2"}], "x_generator": {"engine": "VINCE 3.0.41", "env": "prod", "origin": "https://cveawg.mitre.org/api/cve/CVE-2026-4891"}, "providerMetadata": {"orgId": "37e5125f-f79b-445b-8fad-9564f167944b", "shortName": "certcc", "dateUpdated": "2026-05-20T14:08:50.799Z"}}, "adp": [{"metrics": [{"cvssV3_1": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 5.3, "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "NONE", "privilegesRequired": "NONE", "confidentialityImpact": "LOW"}}, {"other": {"type": "ssvc", "content": {"timestamp": "2026-05-11T18:27:33.459839Z", "id": "CVE-2026-4891", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"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": "2026-05-11T18:27:36.545Z"}}]}}

{"dataType": "CVE_RECORD", "containers": {"adp": [{"title": "CISA ADP Vulnrichment", "metrics": [{"cvssV3_1": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 5.3, "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "NONE", "privilegesRequired": "NONE", "confidentialityImpact": "LOW"}}, {"other": {"type": "ssvc", "content": {"id": "CVE-2026-4891", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "version": "2.0.3", "timestamp": "2026-05-11T18:27:33.459839Z"}}}], "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-05-11T18:27:24.527Z"}}], "cna": {"title": "CVE-2026-4891", "source": {"discovery": "UNKNOWN"}, "affected": [{"vendor": "dnsmasq", "product": "dnsmasq", "versions": [{"status": "affected", "version": "0", "lessThan": "2.92rel2", "versionType": "custom"}]}], "references": [{"url": "https://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2026q2/018471.html"}, {"url": "https://www.kb.cert.org/vuls/id/471747"}, {"url": "https://thekelleys.org.uk/dnsmasq/CVE/"}, {"url": "https://github.com/NixOS/nixpkgs/pull/519082"}, {"url": "https://github.com/NixOS/nixpkgs/pull/519093"}, {"url": "https://github.com/pi-hole/FTL/releases/tag/v6.6.2"}], "x_generator": {"env": "prod", "engine": "VINCE 3.0.41", "origin": "https://cveawg.mitre.org/api/cve/CVE-2026-4891"}, "descriptions": [{"lang": "en", "value": "A heap-based out-of-bounds read vulnerability in the DNSSEC validation of dnsmasq allows remote attackers to cause a denial of service via a crafted DNS packet."}], "problemTypes": [{"descriptions": [{"lang": "en", "description": "CWE-125: Out-of-bounds Read"}]}], "providerMetadata": {"orgId": "37e5125f-f79b-445b-8fad-9564f167944b", "shortName": "certcc", "dateUpdated": "2026-05-20T14:08:50.799Z"}}}, "cveMetadata": {"cveId": "CVE-2026-4891", "state": "PUBLISHED", "dateUpdated": "2026-05-20T14:08:50.799Z", "dateReserved": "2026-03-26T13:07:05.406Z", "assignerOrgId": "37e5125f-f79b-445b-8fad-9564f167944b", "datePublished": "2026-05-11T16:47:33.202Z", "assignerShortName": "certcc"}, "dataVersion": "5.2"}

{"cveTags": [], "descriptions": [{"lang": "en", "value": "A heap-based out-of-bounds read vulnerability in the DNSSEC validation of dnsmasq allows remote attackers to cause a denial of service via a crafted DNS packet."}], "id": "CVE-2026-4891", "lastModified": "2026-05-12T14:15:46.747", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 5.3, "baseSeverity": "MEDIUM", "confidentialityImpact": "LOW", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 1.4, "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary"}]}, "published": "2026-05-11T18:16:41.380", "references": [{"source": "cret@cert.org", "url": "https://github.com/NixOS/nixpkgs/pull/519082"}, {"source": "cret@cert.org", "url": "https://github.com/NixOS/nixpkgs/pull/519093"}, {"source": "cret@cert.org", "url": "https://github.com/pi-hole/FTL/releases/tag/v6.6.2"}, {"source": "cret@cert.org", "url": "https://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2026q2/018471.html"}, {"source": "cret@cert.org", "url": "https://thekelleys.org.uk/dnsmasq/CVE/"}, {"source": "cret@cert.org", "url": "https://www.kb.cert.org/vuls/id/471747"}], "sourceIdentifier": "cret@cert.org", "vulnStatus": "Awaiting Analysis"}

{"bugzilla": {"description": "dnsmasq: RRSIG rdlen underflow leading to heap OOB read", "id": "2458517", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2458517"}, "csaw": false, "cvss3": {"cvss3_base_score": "7.5", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-125", "details": ["A heap out-of-bounds read vulnerability was discovered in dnsmasq's DNSSEC validation. When processing RRSIG records, dnsmasq calculates the signature length by subtracting the fixed field size from the record's declared data length. A crafted RRSIG record with a data length smaller than the fixed fields causes this calculation to underflow, potentially resulting in an out-of-bounds read and process crash."], "name": "CVE-2026-4891", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Affected", "package_name": "dnsmasq", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Will not fix", "package_name": "dnsmasq", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Affected", "package_name": "dnsmasq", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "package_name": "dnsmasq", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "dnsmasq", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/a:redhat:openshift:4", "fix_state": "Affected", "package_name": "rhcos", "product_name": "Red Hat OpenShift Container Platform 4"}], "public_date": "2026-05-09T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-4891\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-4891"], "threat_severity": "Important"}