{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-124740", "assignerOrgId": "53f830b8-0a3f-465b-8143-3b8a9948e749", "state": "PUBLISHED", "assignerShortName": "redhat", "dateReserved": "2026-11-09T11:36:29.478Z", "datePublished": "2026-11-11T11:19:51.920Z", "dateUpdated": "2026-11-11T11:19:51.920Z"}, "containers": {"cna": {"title": "Busybox: use-after-free of requested_ipv6 in udhcpc6", "metrics": [{"other": {"content": {"value": "Moderate", "namespace": "https://access.redhat.com/security/updates/classification/"}, "type": "Red Hat severity rating"}}, {"cvssV3_1": {"attackComplexity": "LOW", "attackVector": "ADJACENT_NETWORK", "availabilityImpact": "LOW", "baseScore": 4.3, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L", "version": "3.1"}, "format": "CVSS"}], "descriptions": [{"lang": "en", "value": "A flaw was found in BusyBox's udhcpc6 DHCPv6 client. A malicious server on the local network can trigger a use-after-free condition by responding with a crafted Dynamic Host Configuration Protocol for IPv6 (DHCPv6) reply packet lacking usable address options. This issue causes the client to read stale heap memory, which can result in a Denial of Service (DoS) due to an application crash or disclose previously assigned network address data in subsequent discovery requests."}], "affected": [{"vendor": "Red Hat", "product": "Red Hat Enterprise Linux 6", "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "packageName": "busybox", "defaultStatus": "unaffected", "cpes": ["cpe:/o:redhat:rhel_els:6"]}, {"vendor": "Red Hat", "product": "Red Hat Hardened Images", "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "packageName": "busybox", "defaultStatus": "affected", "cpes": ["cpe:/a:redhat:hummingbird:1"]}], "references": [{"url": "https://access.redhat.com/security/cve/CVE-2026-124740", "tags": ["vdb-entry", "x_refsource_REDHAT"]}, {"url": "https://bugzilla.redhat.com/show_bug.cgi?id=2571616", "name": "RHBZ#2571616", "tags": ["issue-tracking", "x_refsource_REDHAT"]}], "datePublic": "2026-11-11T09:15:15.000Z", "problemTypes": [{"descriptions": [{"cweId": "CWE-416", "description": "Use After Free", "lang": "en", "type": "CWE"}]}], "x_redhatCweChain": "CWE-416: Use After Free", "workarounds": [{"lang": "en", "value": "Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability."}], "timeline": [{"lang": "en", "time": "2026-10-25T13:37:49.000Z", "value": "Reported to Red Hat."}, {"lang": "en", "time": "2026-11-11T09:15:15.000Z", "value": "Made public."}], "credits": [{"lang": "en", "value": "Red Hat would like to thank ducanhluu for reporting this issue."}], "providerMetadata": {"orgId": "53f830b8-0a3f-465b-8143-3b8a9948e749", "shortName": "redhat", "dateUpdated": "2026-11-11T11:19:51.920Z"}, "x_generator": {"engine": "cvelib 1.8.0"}}}}

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{"affected": [{"affectedData": [{"collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": ["cpe:/o:redhat:rhel_els:6"], "defaultStatus": "unaffected", "packageName": "busybox", "product": "Red Hat Enterprise Linux 6", "vendor": "Red Hat"}, {"collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "cpes": ["cpe:/a:redhat:hummingbird:1"], "defaultStatus": "affected", "packageName": "busybox", "product": "Red Hat Hardened Images", "vendor": "Red Hat"}], "source": "secalert@redhat.com"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "A flaw was found in BusyBox's udhcpc6 DHCPv6 client. A malicious server on the local network can trigger a use-after-free condition by responding with a crafted Dynamic Host Configuration Protocol for IPv6 (DHCPv6) reply packet lacking usable address options. This issue causes the client to read stale heap memory, which can result in a Denial of Service (DoS) due to an application crash or disclose previously assigned network address data in subsequent discovery requests."}], "id": "CVE-2026-124740", "lastModified": "2026-11-11T12:19:47.830", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "ADJACENT_NETWORK", "availabilityImpact": "LOW", "baseScore": 4.3, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L", "version": "3.1"}, "exploitabilityScore": 2.8, "impactScore": 1.4, "source": "secalert@redhat.com", "type": "Primary"}]}, "published": "2026-11-11T12:19:47.710", "references": [{"source": "secalert@redhat.com", "url": "https://access.redhat.com/security/cve/CVE-2026-124740"}, {"source": "secalert@redhat.com", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2571616"}], "sourceIdentifier": "secalert@redhat.com", "vulnStatus": "Awaiting Analysis", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-416"}], "source": "secalert@redhat.com", "type": "Primary"}]}

{"acknowledgement": "Red Hat would like to thank ducanhluu for reporting this issue.", "bugzilla": {"description": "busybox: Use-after-free of requested_ipv6 in udhcpc6", "id": "2571616", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2571616"}, "csaw": false, "cvss3": {"cvss3_base_score": "4.3", "cvss3_scoring_vector": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L", "status": "draft"}, "cwe": "CWE-416", "details": ["A flaw was found in BusyBox's udhcpc6 DHCPv6 client. A malicious server on the local network can trigger a use-after-free condition by responding with a crafted Dynamic Host Configuration Protocol for IPv6 (DHCPv6) reply packet lacking usable address options. This issue causes the client to read stale heap memory, which can result in a Denial of Service (DoS) due to an application crash or disclose previously assigned network address data in subsequent discovery requests."], "mitigation": {"lang": "en:us", "value": "Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability."}, "name": "CVE-2026-124740", "package_state": [{"cpe": "cpe:/o:redhat:rhel_els:6", "fix_state": "Not affected", "package_name": "busybox", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/a:redhat:hummingbird:1", "fix_state": "Affected", "package_name": "busybox", "product_name": "Red Hat Hardened Images"}], "public_date": "2026-11-11T09:15:15Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-124740\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-124740"], "statement": "This vulnerability is classified as Moderate severity because exploitation requires an adjacent attacker on the local network link to operate a rogue DHCPv6 server, and the impact is restricted to stale heap data disclosure in outbound packets or a client denial of service. BusyBox udhcpc6 is not deployed as the default DHCP client in standard Red Hat Enterprise Linux installations, which instead rely on NetworkManager. As a result, the risk is limited to custom environments, containers, or minimal recovery images where the BusyBox DHCPv6 client is specifically executed.", "threat_severity": "Moderate"}

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