---
id: CVE-2026-74667
title: |-
  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 …
summary: |-
  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 …
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
published: '2026-08-22'
updated: '2026-10-14'
sourceUpdated: '2026-10-14T13:10:00.187'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-74667'
references:
  - url: 'https://git.kernel.org/stable/c/1e43a1d66615f411d427f9df1f46dd049d9e3681'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/2610ed4e86a4590234a9d70518c469751c5af231'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/284f3e7a3f1a743fdf89e304fd1f19d5ffcff46d'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/4057853a91fb796c4f47c7d1baf1aa085394148e'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/971aa7d99242bbf09513e27b7a243f0b29ff23ae'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/b47ba8fe6e1d2df8c92048de5afafd059447dc30'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/c2707480cfbf19c7619acc9c089d17f20869821f'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/fdd4d7d52358a58e351dd9d82530c04eba8ccd7a'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
epss: 0.00136
epssPercentile: 0.02625
ingestedAt: '2026-10-14T13:30:58.532Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.