---
id: CVE-2026-31704
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ksmbd: use check_add_overflow() to prevent u16 DACL size overflow

  set_posix_acl_entries_dacl() and set_ntacl_dacl() accumulate ACE sizes
  in u16 variables
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ksmbd: use check_add_overflow() to prevent u16 DACL size overflow

  set_posix_acl_entries_dacl() and set_ntacl_dacl() accumulate ACE sizes
  in u16 variables. When a file …
severity: medium
cvss: 5.5
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 5.15, < 6.6.136'
  - 'linux_kernel >= 6.7, < 6.12.84'
  - 'linux_kernel >= 6.13, < 6.18.25'
  - 'linux_kernel >= 6.19, < 7.0.2'
patched:
  - linux_kernel 7.0.2
published: '2026-05-01'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T02:19:18.803'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-31704'
references:
  - url: 'https://git.kernel.org/stable/c/299f962c0b02d048fb45d248b4da493d03f3175d'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/41e53a773db6342ac9a689ee5ba635c31744c9f0'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/5e7b8f3c539d69b2ed5f2408e2f75e68ce7eef43'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/8d5729350b236896f51379588d9a690b7fafb8db'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/e1955a94b6f17f4b058afa955a6f187eb3ed7615'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/ef7902be3f215b6bf7babe4dc9dd9a7d57dad7a7'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-784472.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
  - cve.org
epss: 0.00162
epssPercentile: 0.05036
ingestedAt: '2026-10-15T03:30:12.867Z'
---

## Overview

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

ksmbd: use check_add_overflow() to prevent u16 DACL size overflow

set_posix_acl_entries_dacl() and set_ntacl_dacl() accumulate ACE sizes
in u16 variables. When a file has many POSIX ACL entries, the
accumulated size can wrap past 65535, causing the pointer arithmetic
(char *)pndace + *size to land within already-written ACEs. Subsequent
writes then overwrite earlier entries, and pndacl->size gets a
truncated value.

Use check_add_overflow() at each accumulation point to detect the
wrap before it corrupts the buffer, consistent with existing
check_mul_overflow() usage elsewhere in smbacl.c.

## Affected

- `linux_kernel >= 5.15, < 6.6.136`
- `linux_kernel >= 6.7, < 6.12.84`
- `linux_kernel >= 6.13, < 6.18.25`
- `linux_kernel >= 6.19, < 7.0.2`

## Remediation

Upgrade past the affected range:

- `linux_kernel 7.0.2`