{"api_version":"1","generated_at":"2026-08-20T20:20:32+00:00","cve":"CVE-2026-72019","urls":{"html":"https://cve.report/CVE-2026-72019","api":"https://cve.report/api/cve/CVE-2026-72019.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-72019","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-72019"},"summary":{"title":"macsec: don't read an unset MAC header in macsec_encrypt()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmacsec: don't read an unset MAC header in macsec_encrypt()\n\nmacsec_encrypt() reads the Ethernet header via eth_hdr(skb)\n(skb->head + skb->mac_header) to memmove() the 12 source/destination MAC\nbytes forward and make room for the SecTAG.\n\nOn the AF_PACKET SOCK_RAW + PACKET_QDISC_BYPASS transmit path the skb\nreaches the macsec ndo_start_xmit() with the MAC header unset, so\neth_hdr(skb) resolves to skb->head + (u16)~0 and the read is out of\nbounds: a 12-byte heap over-read that is also emitted on the wire as the\nframe's outer source/destination MAC. KASAN reports a slab-out-of-bounds\nread in macsec_start_xmit() on 6.0; on current mainline a CONFIG_DEBUG_NET\nbuild flags it as an unset mac header in skb_mac_header().\n\nOn the TX path the L2 header is at skb->data, so use skb_eth_hdr(), added\nby commit 96cc4b69581d (\"macvlan: do not assume mac_header is set in\nmacvlan_broadcast()\") for exactly this purpose.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-08-15 06:21:00","updated_at":"2026-08-17 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Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-72019","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected c09440f7dcb304002dfced8c0fea289eb25f2da0 b6cec6187b8632423cd99a94fd5e5ba165fa2a33 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected c09440f7dcb304002dfced8c0fea289eb25f2da0 3adea1b1c04b57e08a5c12a1f42483760581ce61 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected c09440f7dcb304002dfced8c0fea289eb25f2da0 dc9ffa1905e72f026d080880a2e4cfc42aa91000 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected c09440f7dcb304002dfced8c0fea289eb25f2da0 f21fa533a3ed15ada74106aac4b9ddd078fc6b7a git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 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original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"72019","cve":"CVE-2026-72019","epss":"0.001670000","percentile":"0.064760000","score_date":"2026-08-19","updated_at":"2026-08-20 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the Linux kernel, the following vulnerability has been resolved:\n\nmacsec: don't read an unset MAC header in macsec_encrypt()\n\nmacsec_encrypt() reads the Ethernet header via eth_hdr(skb)\n(skb->head + skb->mac_header) to memmove() the 12 source/destination MAC\nbytes forward and make room for the SecTAG.\n\nOn the AF_PACKET SOCK_RAW + PACKET_QDISC_BYPASS transmit path the skb\nreaches the macsec ndo_start_xmit() with the MAC header unset, so\neth_hdr(skb) resolves to skb->head + (u16)~0 and the read is out of\nbounds: a 12-byte heap over-read that is also emitted on the wire as the\nframe's outer source/destination MAC. KASAN reports a slab-out-of-bounds\nread in macsec_start_xmit() on 6.0; on current mainline a CONFIG_DEBUG_NET\nbuild flags it as an unset mac header in skb_mac_header().\n\nOn the TX path the L2 header is at skb->data, so use skb_eth_hdr(), added\nby commit 96cc4b69581d (\"macvlan: do not assume mac_header is set in\nmacvlan_broadcast()\") for exactly this purpose."}],"metrics":[{"cvssV3_1":{"baseScore":7.3,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H","version":"3.1"},"scenarios":[{"lang":"en","value":"AV:L - The bug is reached only via local AF_PACKET SOCK_RAW transmit with PACKET_QDISC_BYPASS to a macsec netdev; it is a TX-only ndo_start_xmit path, not reachable from remote network packet reception.\nAC:L - An attacker fully controls the trigger: create a raw packet socket with a specific ethertype, enable PACKET_QDISC_BYPASS, and send a frame on a configured macsec interface with protect_frames enabled.\nPR:L - Exploitation requires CAP_NET_RAW for AF_PACKET and CAP_NET_ADMIN to create/configure a macsec netdev and TX SA keys; both are obtainable by an unprivileged user inside a user namespace with delegated capabilities.\nUI:N - No victim interaction is required; the attacker sends crafted frames directly through the vulnerable transmit path without any action from another user or administrator.\nS:U - Impact is confined to kernel heap disclosure and possible kernel crash on the same host; it does not cross a VM, container, or IOMMU security boundary to affect a separate authority.\nC:H - eth_hdr(skb) performs a 12-byte slab out-of-bounds heap read when mac_header is unset; the leaked kernel memory is copied into the transmitted frame's source/destination MAC fields, disclosing sensitive heap contents.\nI:L - The memmove in macsec_encrypt() overwrites the outgoing frame's 12-byte Ethernet addresses with leaked heap data, causing unauthorized modification of transmitted packet contents without arbitrary kernel memory writes.\nA:H - Reading from skb->head plus unset mac_header offset 65535 causes a slab out-of-bounds access that KASAN flags and can page-fault into a kernel oops or panic when macsec_encrypt() runs on affected builds."}]}],"providerMetadata":{"dateUpdated":"2026-08-19T16:35:53.169Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/b6cec6187b8632423cd99a94fd5e5ba165fa2a33"},{"url":"https://git.kernel.org/stable/c/3adea1b1c04b57e08a5c12a1f42483760581ce61"},{"url":"https://git.kernel.org/stable/c/dc9ffa1905e72f026d080880a2e4cfc42aa91000"},{"url":"https://git.kernel.org/stable/c/f21fa533a3ed15ada74106aac4b9ddd078fc6b7a"},{"url":"https://git.kernel.org/stable/c/e17a42199824973cd8212e95b21ffadf4114a21b"},{"url":"https://git.kernel.org/stable/c/2cf10d042562283ff4ae97c02d0993d4f1b5ea29"},{"url":"https://git.kernel.org/stable/c/c39087ad0b97fc11a3b058dfc8db9fd370762cb9"},{"url":"https://git.kernel.org/stable/c/f5089008f90c0a7c5520dff3934e0af00adf322d"}],"title":"macsec: don't read an unset MAC header in macsec_encrypt()","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-72019","datePublished":"2026-08-15T05:51:46.014Z","dateReserved":"2026-08-09T03:40:39.900Z","dateUpdated":"2026-08-19T16:35:53.169Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-08-15 06:21:00","lastModifiedDate":"2026-08-17 06:17:59","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H","baseScore":7.3,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"LOW","availabilityImpact":"HIGH"},"exploitabilityScore":1.8,"impactScore":5.5}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"72019","Ordinal":"1","Title":"macsec: don't read an unset MAC header in macsec_encrypt()","CVE":"CVE-2026-72019","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"72019","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nmacsec: don't read an unset MAC header in macsec_encrypt()\n\nmacsec_encrypt() reads the Ethernet header via eth_hdr(skb)\n(skb->head + skb->mac_header) to memmove() the 12 source/destination MAC\nbytes forward and make room for the SecTAG.\n\nOn the AF_PACKET SOCK_RAW + PACKET_QDISC_BYPASS transmit path the skb\nreaches the macsec ndo_start_xmit() with the MAC header unset, so\neth_hdr(skb) resolves to skb->head + (u16)~0 and the read is out of\nbounds: a 12-byte heap over-read that is also emitted on the wire as the\nframe's outer source/destination MAC. KASAN reports a slab-out-of-bounds\nread in macsec_start_xmit() on 6.0; on current mainline a CONFIG_DEBUG_NET\nbuild flags it as an unset mac header in skb_mac_header().\n\nOn the TX path the L2 header is at skb->data, so use skb_eth_hdr(), added\nby commit 96cc4b69581d (\"macvlan: do not assume mac_header is set in\nmacvlan_broadcast()\") for exactly this purpose.","Type":"Description","Title":"macsec: don't read an unset MAC header in macsec_encrypt()"}]}}}