---
id: CVE-2026-72351
title: 'gue: validate REMCSUM private option length'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  gue: validate REMCSUM private option length

  GUE private flags can indicate that remote checksum offload metadata is
  present. The private flags field itself is accounte…
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= c1aa8347e73e4092411fbd96cc59531fb7e76d04 <
    158b9995d3c87f3b93f5c22df54a12e12a3438b3
  - >-
    Linux >= c1aa8347e73e4092411fbd96cc59531fb7e76d04 <
    7c6876ec1b227261b51803f784c7be1b2242a1a0
  - >-
    Linux >= c1aa8347e73e4092411fbd96cc59531fb7e76d04 <
    2c4de9988e9ddc760b750d6b6e701c35ff60ad14
  - >-
    Linux >= c1aa8347e73e4092411fbd96cc59531fb7e76d04 <
    2a99224c120823987e4d829726f4ecb33e03fc1e
  - >-
    Linux >= c1aa8347e73e4092411fbd96cc59531fb7e76d04 <
    61e78679c7c9ca685bff58e4b6348304dc60aafd
  - >-
    Linux >= c1aa8347e73e4092411fbd96cc59531fb7e76d04 <
    4a4a1d41c6e901e773bcf795f562a47fa71f692a
  - >-
    Linux >= c1aa8347e73e4092411fbd96cc59531fb7e76d04 <
    f618cbe9b24cd0202004d2db781d5f80ab77037f
  - >-
    Linux >= c1aa8347e73e4092411fbd96cc59531fb7e76d04 <
    d335dcc6f521571d57117b8deeebc940836e5450
  - Linux 3.19
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: total
  timestamp: '2026-10-16T18:47:48.615145Z'
published: '2026-08-15'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T18:55:19.979Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-72351'
references:
  - url: 'https://git.kernel.org/stable/c/158b9995d3c87f3b93f5c22df54a12e12a3438b3'
  - url: 'https://git.kernel.org/stable/c/7c6876ec1b227261b51803f784c7be1b2242a1a0'
  - url: 'https://git.kernel.org/stable/c/2c4de9988e9ddc760b750d6b6e701c35ff60ad14'
  - url: 'https://git.kernel.org/stable/c/2a99224c120823987e4d829726f4ecb33e03fc1e'
  - url: 'https://git.kernel.org/stable/c/61e78679c7c9ca685bff58e4b6348304dc60aafd'
  - url: 'https://git.kernel.org/stable/c/4a4a1d41c6e901e773bcf795f562a47fa71f692a'
  - url: 'https://git.kernel.org/stable/c/f618cbe9b24cd0202004d2db781d5f80ab77037f'
  - url: 'https://git.kernel.org/stable/c/d335dcc6f521571d57117b8deeebc940836e5450'
tags:
  - cve.org
epss: 0.00745
epssPercentile: 0.53884
ingestedAt: '2026-10-16T19:46:24.403Z'
---

## Overview

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

gue: validate REMCSUM private option length

GUE private flags can indicate that remote checksum offload metadata is
present. The private flags field itself is accounted for by
guehdr_flags_len(), but guehdr_priv_flags_len() currently returns 0 even
when GUE_PFLAG_REMCSUM is set.

This lets a packet with only the private flags field pass
validate_gue_flags(), after which gue_remcsum() and gue_gro_remcsum()
read the missing REMCSUM start/offset fields from the following bytes.

Account for GUE_PLEN_REMCSUM when GUE_PFLAG_REMCSUM is present so that
malformed packets are rejected during option validation.

## Affected

- `Linux >= c1aa8347e73e4092411fbd96cc59531fb7e76d04 < 158b9995d3c87f3b93f5c22df54a12e12a3438b3`
- `Linux >= c1aa8347e73e4092411fbd96cc59531fb7e76d04 < 7c6876ec1b227261b51803f784c7be1b2242a1a0`
- `Linux >= c1aa8347e73e4092411fbd96cc59531fb7e76d04 < 2c4de9988e9ddc760b750d6b6e701c35ff60ad14`
- `Linux >= c1aa8347e73e4092411fbd96cc59531fb7e76d04 < 2a99224c120823987e4d829726f4ecb33e03fc1e`
- `Linux >= c1aa8347e73e4092411fbd96cc59531fb7e76d04 < 61e78679c7c9ca685bff58e4b6348304dc60aafd`
- `Linux >= c1aa8347e73e4092411fbd96cc59531fb7e76d04 < 4a4a1d41c6e901e773bcf795f562a47fa71f692a`
- `Linux >= c1aa8347e73e4092411fbd96cc59531fb7e76d04 < f618cbe9b24cd0202004d2db781d5f80ab77037f`
- `Linux >= c1aa8347e73e4092411fbd96cc59531fb7e76d04 < d335dcc6f521571d57117b8deeebc940836e5450`
- `Linux 3.19`

## Remediation

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