CVE-2026-72019 (GCVE-0-2026-72019)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:51 – Updated: 2026-08-19 16:35
VLAI
Title
macsec: don't read an unset MAC header in macsec_encrypt()
Summary
In the Linux kernel, the following vulnerability has been resolved: macsec: don't read an unset MAC header in macsec_encrypt() macsec_encrypt() reads the Ethernet header via eth_hdr(skb) (skb->head + skb->mac_header) to memmove() the 12 source/destination MAC bytes forward and make room for the SecTAG. On the AF_PACKET SOCK_RAW + PACKET_QDISC_BYPASS transmit path the skb reaches the macsec ndo_start_xmit() with the MAC header unset, so eth_hdr(skb) resolves to skb->head + (u16)~0 and the read is out of bounds: a 12-byte heap over-read that is also emitted on the wire as the frame's outer source/destination MAC. KASAN reports a slab-out-of-bounds read in macsec_start_xmit() on 6.0; on current mainline a CONFIG_DEBUG_NET build flags it as an unset mac header in skb_mac_header(). On the TX path the L2 header is at skb->data, so use skb_eth_hdr(), added by commit 96cc4b69581d ("macvlan: do not assume mac_header is set in macvlan_broadcast()") for exactly this purpose.
Severity
7.3 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: c09440f7dcb304002dfced8c0fea289eb25f2da0 , < b6cec6187b8632423cd99a94fd5e5ba165fa2a33 (git)
Affected: c09440f7dcb304002dfced8c0fea289eb25f2da0 , < 3adea1b1c04b57e08a5c12a1f42483760581ce61 (git)
Affected: c09440f7dcb304002dfced8c0fea289eb25f2da0 , < dc9ffa1905e72f026d080880a2e4cfc42aa91000 (git)
Affected: c09440f7dcb304002dfced8c0fea289eb25f2da0 , < f21fa533a3ed15ada74106aac4b9ddd078fc6b7a (git)
Affected: c09440f7dcb304002dfced8c0fea289eb25f2da0 , < e17a42199824973cd8212e95b21ffadf4114a21b (git)
Affected: c09440f7dcb304002dfced8c0fea289eb25f2da0 , < 2cf10d042562283ff4ae97c02d0993d4f1b5ea29 (git)
Affected: c09440f7dcb304002dfced8c0fea289eb25f2da0 , < c39087ad0b97fc11a3b058dfc8db9fd370762cb9 (git)
Affected: c09440f7dcb304002dfced8c0fea289eb25f2da0 , < f5089008f90c0a7c5520dff3934e0af00adf322d (git)
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Linux Linux Affected: 4.6
Unaffected: 0 , < 4.6 (semver)
Unaffected: 5.10.265 , ≤ 5.10.* (semver)
Unaffected: 5.15.216 , ≤ 5.15.* (semver)
Unaffected: 6.1.178 , ≤ 6.1.* (semver)
Unaffected: 6.6.145 , ≤ 6.6.* (semver)
Unaffected: 6.12.97 , ≤ 6.12.* (semver)
Unaffected: 6.18.40 , ≤ 6.18.* (semver)
Unaffected: 7.1.5 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmacsec: don\u0027t read an unset MAC header in macsec_encrypt()\n\nmacsec_encrypt() reads the Ethernet header via eth_hdr(skb)\n(skb-\u003ehead + skb-\u003emac_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-\u003ehead + (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\u0027s 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-\u003edata, so use skb_eth_hdr(), added\nby commit 96cc4b69581d (\"macvlan: do not assume mac_header is set in\nmacvlan_broadcast()\") for exactly this purpose."
        }
      ],
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            "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\u0027s source/destination MAC fields, disclosing sensitive heap contents.\nI:L - The memmove in macsec_encrypt() overwrites the outgoing frame\u0027s 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-\u003ehead 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."
            }
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        "dateUpdated": "2026-08-19T16:35:53.169Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/b6cec6187b8632423cd99a94fd5e5ba165fa2a33"
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          "url": "https://git.kernel.org/stable/c/3adea1b1c04b57e08a5c12a1f42483760581ce61"
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      "title": "macsec: don\u0027t read an unset MAC header in macsec_encrypt()",
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    "assignerShortName": "Linux",
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    "datePublished": "2026-08-15T05:51:46.014Z",
    "dateReserved": "2026-08-09T03:40:39.900Z",
    "dateUpdated": "2026-08-19T16:35:53.169Z",
    "state": "PUBLISHED"
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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-\u003edata, so use skb_eth_hdr(), added\\nby commit 96cc4b69581d (\\\"macvlan: do not assume mac_header is set in\\nmacvlan_broadcast()\\\") for exactly this purpose.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"drivers/net/macsec.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"c09440f7dcb304002dfced8c0fea289eb25f2da0\",\"lessThan\":\"b6cec6187b8632423cd99a94fd5e5ba165fa2a33\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"c09440f7dcb304002dfced8c0fea289eb25f2da0\",\"lessThan\":\"3adea1b1c04b57e08a5c12a1f42483760581ce61\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"c09440f7dcb304002dfced8c0fea289eb25f2da0\",\"lessThan\":\"dc9ffa1905e72f026d080880a2e4cfc42aa91000\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"c09440f7dcb304002dfced8c0fea289eb25f2da0\",\"lessThan\":\"f21fa533a3ed15ada74106aac4b9ddd078fc6b7a\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"c09440f7dcb304002dfced8c0fea289eb25f2da0\",\"lessThan\":\"e17a42199824973cd8212e95b21ffadf4114a21b\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"c09440f7dcb304002dfced8c0fea289eb25f2da0\",\"lessThan\":\"2cf10d042562283ff4ae97c02d0993d4f1b5ea29\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"c09440f7dcb304002dfced8c0fea289eb25f2da0\",\"lessThan\":\"c39087ad0b97fc11a3b058dfc8db9fd370762cb9\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"c09440f7dcb304002dfced8c0fea289eb25f2da0\",\"lessThan\":\"f5089008f90c0a7c5520dff3934e0af00adf322d\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"drivers/net/macsec.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"4.6\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"4.6\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"5.10.265\",\"lessThanOrEqual\":\"5.10.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"5.15.216\",\"lessThanOrEqual\":\"5.15.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.1.178\",\"lessThanOrEqual\":\"6.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.6.145\",\"lessThanOrEqual\":\"6.6.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.97\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.40\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1.5\",\"lessThanOrEqual\":\"7.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"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}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/2cf10d042562283ff4ae97c02d0993d4f1b5ea29\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/3adea1b1c04b57e08a5c12a1f42483760581ce61\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/b6cec6187b8632423cd99a94fd5e5ba165fa2a33\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/c39087ad0b97fc11a3b058dfc8db9fd370762cb9\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/dc9ffa1905e72f026d080880a2e4cfc42aa91000\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/e17a42199824973cd8212e95b21ffadf4114a21b\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/f21fa533a3ed15ada74106aac4b9ddd078fc6b7a\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/f5089008f90c0a7c5520dff3934e0af00adf322d\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-17T14:55:13+00:00",
      "cve": "CVE-2026-72019",
      "id": "CVE-2026-72019",
      "initial_release_date": "2026-08-15T00:00:00+00:00",
      "product_status:known_affected": "260",
      "product_status:known_not_affected": "14",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: macsec: don\u0027t read an unset MAC header in macsec_encrypt()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-72019.json",
      "version": "3"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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