---
id: CVE-2026-90153
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ksmbd: bound smb_check_perm_dacl() ACE walks by DACL size

  smb_check_perm_dacl() validates that the DACL fits inside the NT
  security descriptor, but then bounds its two…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ksmbd: bound smb_check_perm_dacl() ACE walks by DACL size

  smb_check_perm_dacl() validates that the DACL fits inside the NT
  security descriptor, but then bounds its two…
severity: high
cvss: 8.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N'
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 8f0541186e9ad1b62accc9519cc2b7a7240272a7 <
    a2051ffe452afad52f580b85a3fd8851933b1e7c
  - >-
    Linux >= 8f0541186e9ad1b62accc9519cc2b7a7240272a7 <
    a29f57a14c939586d84d7fd6a029bd1fd170098f
  - >-
    Linux >= 8f0541186e9ad1b62accc9519cc2b7a7240272a7 <
    a4a307d149327dad5fb25187e1b03cebd1b04de6
  - >-
    Linux >= 8f0541186e9ad1b62accc9519cc2b7a7240272a7 <
    8e4f75e979c1d9a51b0a48ac33d0cfd5f039ec67
  - >-
    Linux >= 8f0541186e9ad1b62accc9519cc2b7a7240272a7 <
    79decd88dd3f0d42e7fb0689b1a7853bfa302459
  - Linux cb69d4d6f709f87c94afa28ae64c501576692171
  - Linux 6e8f4abf584253cbaa596ea4ad13110cf61cd4c9
  - Linux 8e33102309bd6839b2e2e158f93a7b378cb4655d
  - Linux >= 5.15.62 < 5.16
  - Linux >= 5.18.18 < 5.19
  - Linux >= 5.19.2 < 5.20
  - Linux 6.0
published: '2026-09-17'
updated: '2026-09-18'
sourceUpdated: '2026-09-18T18:17:44.427'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-90153'
references:
  - url: 'https://git.kernel.org/stable/c/79decd88dd3f0d42e7fb0689b1a7853bfa302459'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/8e4f75e979c1d9a51b0a48ac33d0cfd5f039ec67'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/a2051ffe452afad52f580b85a3fd8851933b1e7c'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/a29f57a14c939586d84d7fd6a029bd1fd170098f'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/a4a307d149327dad5fb25187e1b03cebd1b04de6'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
epss: 0.00445
epssPercentile: 0.38146
ingestedAt: '2026-09-17T16:21:47.874Z'
---

## Overview

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

ksmbd: bound smb_check_perm_dacl() ACE walks by DACL size

smb_check_perm_dacl() validates that the DACL fits inside the NT
security descriptor, but then bounds its two ACE walks by the
remaining NTSD length (acl_size) rather than the DACL's declared
size (pdacl_size).

When pdacl->size is smaller than the trailing NTSD buffer, bytes
after the declared DACL boundary - still inside the stored security
descriptor - are parsed as ACEs during access checks.  A crafted
DACL can place an access-granting ACE beyond pdacl->size, and the
current code accepts it during SMB2_CREATE access validation, while
parse_dacl() and smb_inherit_dacl() stop at pdacl_size.

Bound both ACE walks by pdacl_size to match the DACL boundary
semantics used elsewhere in the server.

Validation:
- semantic KUnit harness shows the post-boundary ACE is selected
  before the fix and rejected (EACCES) after it
- linux master (7.2-rc6), x86_64

## Remediation

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