---
id: CVE-2026-68385
title: 's390/checksum: Fix csum_partial() without vector facility'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  s390/checksum: Fix csum_partial() without vector facility

  Currently csum_partial() calls csum_copy() with copy=false and dst=NULL.
  On machines without the vector facil…
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 >= dcd3e1de9d17dc43dfed87a9fc814b9dec508043 <
    5fc0a2a6eeb99cac991242bb48796c7749ce3261
  - >-
    Linux >= dcd3e1de9d17dc43dfed87a9fc814b9dec508043 <
    1d9a2f01b3c4e5c88e06b2db4b5460c2ec884722
  - >-
    Linux >= dcd3e1de9d17dc43dfed87a9fc814b9dec508043 <
    898bb2814f38399108bdd2113f38d97383a7036a
  - >-
    Linux >= dcd3e1de9d17dc43dfed87a9fc814b9dec508043 <
    4bb06b60d982355e22647b3d12d6619419f8c1fa
  - Linux 6.9
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: total
  timestamp: '2026-10-16T15:47:51.059677Z'
published: '2026-08-10'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T15:53:10.849Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-68385'
references:
  - url: 'https://git.kernel.org/stable/c/5fc0a2a6eeb99cac991242bb48796c7749ce3261'
  - url: 'https://git.kernel.org/stable/c/1d9a2f01b3c4e5c88e06b2db4b5460c2ec884722'
  - url: 'https://git.kernel.org/stable/c/898bb2814f38399108bdd2113f38d97383a7036a'
  - url: 'https://git.kernel.org/stable/c/4bb06b60d982355e22647b3d12d6619419f8c1fa'
tags:
  - cve.org
epss: 0.00491
epssPercentile: 0.40779
ingestedAt: '2026-10-16T17:24:46.862Z'
---

## Overview

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

s390/checksum: Fix csum_partial() without vector facility

Currently csum_partial() calls csum_copy() with copy=false and dst=NULL.
On machines without the vector facility, csum_copy() falls back to
cksm(dst, ...), causing the checksum to be calculated from address zero
instead of the source buffer.

The VX implementation already checksums data loaded from src. Make the
fallback do the same by passing src to cksm().

## Affected

- `Linux >= dcd3e1de9d17dc43dfed87a9fc814b9dec508043 < 5fc0a2a6eeb99cac991242bb48796c7749ce3261`
- `Linux >= dcd3e1de9d17dc43dfed87a9fc814b9dec508043 < 1d9a2f01b3c4e5c88e06b2db4b5460c2ec884722`
- `Linux >= dcd3e1de9d17dc43dfed87a9fc814b9dec508043 < 898bb2814f38399108bdd2113f38d97383a7036a`
- `Linux >= dcd3e1de9d17dc43dfed87a9fc814b9dec508043 < 4bb06b60d982355e22647b3d12d6619419f8c1fa`
- `Linux 6.9`

## Remediation

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