---
id: CVE-2026-80731
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net: remove CAP_SYS_RAWIO zero-padding in dev_validate_header

  dev_validate_header() reads dev->hard_header_len directly when
  zero-padding short link layer headers for …
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net: remove CAP_SYS_RAWIO zero-padding in dev_validate_header

  dev_validate_header() reads dev->hard_header_len directly when
  zero-padding short link layer headers for …
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'
cwe:
  - CWE-787
vendor: Red Hat
product: Red Hat Enterprise Linux 9
affected:
  - enterprise_linux 10
  - enterprise_linux 8
  - enterprise_linux 9
  - openshift_container_platform 4
published: '2026-09-03'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T20:18:09.420'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-80731'
references:
  - url: 'https://git.kernel.org/stable/c/3b9a324e646d3657a8d9806dfbfe4f3e4066e882'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/53fd7f912c0877647d6a1e1877f5ea8535ee0b4a'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/74e035f07f53feca09e2352e77fccb09cad5e208'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/8fc9816404166a90ed8d544dc52482fafffb6d9f'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/99df6b7a713f96eda206680d100b76e15f9d9b69'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/b0f92a5731dc82556a9ae005cc35f71ab136307b'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/dbb30dc943a93e083f1e531bfdc6779e57de40d0'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/fa6d98dd925e72fc028b26a0cbbff9d2f0601ff6'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/fc902f52a02298c7432b2334c0c82a2885a1a8b6'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-80731.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-80731'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2527871'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-80731'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-80731'
  - url: >-
      https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-80731.mbox
  - url: 'https://kernelcve.org/list/?q=CVE-2026-80731'
tags:
  - nvd
  - csaf
  - vex
  - red-hat
  - cve.org
  - score-dispute
epss: 0.00142
epssPercentile: 0.03439
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-16T19:21:14.341917Z'
scores:
  nvd: 7.8
  vendor: 4.7
  cna: 7.8
ingestedAt: '2026-10-16T19:46:24.301Z'
---

## Overview

In the Linux kernel, the following vulnerability has been resolved:

net: remove CAP_SYS_RAWIO zero-padding in dev_validate_header

dev_validate_header() reads dev->hard_header_len directly when
zero-padding short link layer headers for CAP_SYS_RAWIO holders:

    if (capable(CAP_SYS_RAWIO)) {
        memset(ll_header + len, 0, dev->hard_header_len - len);
        return true;
    }

Packet send paths call dev_validate_header() on skbs whose headroom was
allocated from an earlier hard_header_len read. If the device is
reconfigured so that dev->hard_header_len increases before validation,
the memset writes past the reserved buffer, an out-of-bounds write.

This out-of-bounds write is masked in some SOCK_RAW paths today because
the same concurrent increase can first make skb_push() exceed the
reserved headroom and trigger skb_under_panic(). Remove the zero-padding
branch before making those hard_header_len reads consistent, so the
snapshot fixes do not turn a loud panic into a silent overwrite.

This path is only reached for variable length L2 protocols, where
len < hard_header_len but len >= min_header_len. No remaining in-tree
variable length L2 protocol implements header_ops->validate, and the
CAP_SYS_RAWIO bypass that zero-pads and accepts short headers has no
real value beyond allowing testing of intentionally malformed input.

Drop the CAP_SYS_RAWIO branch. The remaining reads of
dev->hard_header_len in dev_validate_header() are comparisons only and
have no memory safety impact.

## Remediation

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

## Vendor advisories

- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · updated 2026-10-26 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-80731.json)