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net/packet: reset the MAC header on the packet-socket transmit path

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: net/packet: reset the MAC header on the packet-socket transmit path packet_parse_headers() resets the MAC header only for a SOCK_RAW frame whose socket did not bind a protocol. A protocol-bound SOCK_RAW socket, any SOCK_DGRAM frame, and the legacy SOCK_PACKET path therefore leave skb->mac_header unset here. For frames sent via __dev_queue_xmit() this is harmless: it resets the MAC header unconditionally. But the packet-socket PACKET_QDISC_BYPASS path uses dev_direct_xmit(), which does not, so the frame reaches ndo_start_xmit() with the MAC header unset. A driver that reads eth_hdr(skb) on transmit then dereferences skb->head + (u16)~0, an out-of-bounds access ~64 KiB past the head -- the same class fixed for one consumer in commit f5089008f90c ("macsec: do not read an unset MAC header in macsec_encrypt()"). packet_parse_headers() runs only on the transmit path, where skb->data points at the start of the L2 header for every packet-socket type regardless of its length: SOCK_RAW and SOCK_PACKET carry a user-supplied header and SOCK_DGRAM has one built by dev_hard_header(). Reset the MAC header unconditionally, mirroring __dev_queue_xmit(), so the frame is anchored on the bypass path too. Found by 0sec (https://0sec.ai) using automated source analysis; verified against source and matched to the macsec KASAN report in f5089008f90c. Compile-tested.

Announced Source revision 1
Original source ↗

CVE-2026-74667

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-74667

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Linux

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "75c65772c3d18447d62d3aca5f91b06c16cc25e4",
        "lessThan": "1e43a1d66615f411d427f9df1f46dd049d9e3681",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "75c65772c3d18447d62d3aca5f91b06c16cc25e4",
        "lessThan": "4057853a91fb796c4f47c7d1baf1aa085394148e",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "75c65772c3d18447d62d3aca5f91b06c16cc25e4",
        "lessThan": "2610ed4e86a4590234a9d70518c469751c5af231",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "75c65772c3d18447d62d3aca5f91b06c16cc25e4",
        "lessThan": "b47ba8fe6e1d2df8c92048de5afafd059447dc30",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "75c65772c3d18447d62d3aca5f91b06c16cc25e4",
        "lessThan": "284f3e7a3f1a743fdf89e304fd1f19d5ffcff46d",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "75c65772c3d18447d62d3aca5f91b06c16cc25e4",
        "lessThan": "971aa7d99242bbf09513e27b7a243f0b29ff23ae",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "75c65772c3d18447d62d3aca5f91b06c16cc25e4",
        "lessThan": "fdd4d7d52358a58e351dd9d82530c04eba8ccd7a",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "75c65772c3d18447d62d3aca5f91b06c16cc25e4",
        "lessThan": "c2707480cfbf19c7619acc9c089d17f20869821f",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "net/packet/af_packet.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "5.1"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "5.1",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "5.10.265",
        "versionType": "semver",
        "lessThanOrEqual": "5.10.*"
      },
      {
        "status": "unaffected",
        "version": "5.15.216",
        "versionType": "semver",
        "lessThanOrEqual": "5.15.*"
      },
      {
        "status": "unaffected",
        "version": "6.1.183",
        "versionType": "semver",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.152",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.104",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.45",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "7.1.9",
        "versionType": "semver",
        "lessThanOrEqual": "7.1.*"
      },
      {
        "status": "unaffected",
        "version": "7.2",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "net/packet/af_packet.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-74667

Source reference: /cveMetadata/cveId

Publisher severity

high

Source reference: /containers/cna/metrics

Event
#34265 · Revision 1
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Publisher date
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