GHSA-593P-5684-69PQ

Vulnerability from github – Published: 2026-08-15 06:32 – Updated: 2026-08-19 18:32
VLAI
Details

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
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{
  "affected": [],
  "aliases": [
    "CVE-2026-72019"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-15T06:21:00Z",
    "severity": "HIGH"
  },
  "details": "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.",
  "id": "GHSA-593p-5684-69pq",
  "modified": "2026-08-19T18:32:27Z",
  "published": "2026-08-15T06:32:09Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-72019"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2cf10d042562283ff4ae97c02d0993d4f1b5ea29"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3adea1b1c04b57e08a5c12a1f42483760581ce61"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b6cec6187b8632423cd99a94fd5e5ba165fa2a33"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c39087ad0b97fc11a3b058dfc8db9fd370762cb9"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/dc9ffa1905e72f026d080880a2e4cfc42aa91000"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e17a42199824973cd8212e95b21ffadf4114a21b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f21fa533a3ed15ada74106aac4b9ddd078fc6b7a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f5089008f90c0a7c5520dff3934e0af00adf322d"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H",
      "type": "CVSS_V3"
    }
  ]
}



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