---
id: CVE-2026-46139
title: 'smb: client: use kzalloc to zero-initialize security descriptor buffer'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  smb: client: use kzalloc to zero-initialize security descriptor buffer

  Commit 62e7dd0a39c2d ("smb: common: change the data type of num_aces
  to le16") split struct smb_…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 1593ddb37bd124c131fe635397df68e854a03108 <
    4c3ed344a970aad51388ac3b0145b98318f0e21f
  - >-
    Linux >= da087905e3270e2291c0afae39a28e7d183e5ec3 <
    941a1e6eb35440336913afc88a82103291956d5d
  - >-
    Linux >= 62e7dd0a39c2d0d7ff03274c36df971f1b3d2d0d <
    be1ef9512a3f5a755895c24f31b334342f4aa15b
  - >-
    Linux >= 62e7dd0a39c2d0d7ff03274c36df971f1b3d2d0d <
    9bdb2ca31368b7671949dfb94a5d57ffccd01edd
  - >-
    Linux >= 62e7dd0a39c2d0d7ff03274c36df971f1b3d2d0d <
    5e489c6c47a2ac15edbaca153b9348e42c1eacab
  - Linux 191f2f444745087c3c51fd6042a0e25f42315ab0
  - Linux >= 6.12.23 < 6.12.88
  - Linux >= 6.13.11 < 6.14
  - Linux 6.14
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-11-06T16:09:37.647152Z'
published: '2026-05-28'
updated: '2026-11-06'
sourceUpdated: '2026-11-06T16:13:40.706Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-46139'
references:
  - url: 'https://git.kernel.org/stable/c/4c3ed344a970aad51388ac3b0145b98318f0e21f'
  - url: 'https://git.kernel.org/stable/c/941a1e6eb35440336913afc88a82103291956d5d'
  - url: 'https://git.kernel.org/stable/c/be1ef9512a3f5a755895c24f31b334342f4aa15b'
  - url: 'https://git.kernel.org/stable/c/9bdb2ca31368b7671949dfb94a5d57ffccd01edd'
  - url: 'https://git.kernel.org/stable/c/5e489c6c47a2ac15edbaca153b9348e42c1eacab'
tags:
  - cve.org
epss: 0.00122
epssPercentile: 0.01984
ingestedAt: '2026-11-06T16:57:43.332Z'
---

## Overview

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

smb: client: use kzalloc to zero-initialize security descriptor buffer

Commit 62e7dd0a39c2d ("smb: common: change the data type of num_aces
to le16") split struct smb_acl's __le32 num_aces field into __le16
num_aces and __le16 reserved. The reserved field corresponds to Sbz2
in the MS-DTYP ACL wire format, which must be zero [1].

When building an ACL descriptor in build_sec_desc(), we are using a
kmalloc()'ed descriptor buffer and writing the fields explicitly using
le16() writes now. This never writes to the 2 byte reserved field,
leaving it as uninitialized heap data.

When the reserved field happens to contain non-zero slab garbage,
Samba rejects the security descriptor with "ndr_pull_security_descriptor
failed: Range Error", causing chmod to fail with EINVAL.

Change kmalloc() to kzalloc() to ensure the entire buffer is
zero-initialized.


[1] https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-dtyp/20233ed8-a6c6-4097-aafa-dd545ed24428

## Affected

- `Linux >= 1593ddb37bd124c131fe635397df68e854a03108 < 4c3ed344a970aad51388ac3b0145b98318f0e21f`
- `Linux >= da087905e3270e2291c0afae39a28e7d183e5ec3 < 941a1e6eb35440336913afc88a82103291956d5d`
- `Linux >= 62e7dd0a39c2d0d7ff03274c36df971f1b3d2d0d < be1ef9512a3f5a755895c24f31b334342f4aa15b`
- `Linux >= 62e7dd0a39c2d0d7ff03274c36df971f1b3d2d0d < 9bdb2ca31368b7671949dfb94a5d57ffccd01edd`
- `Linux >= 62e7dd0a39c2d0d7ff03274c36df971f1b3d2d0d < 5e489c6c47a2ac15edbaca153b9348e42c1eacab`
- `Linux 191f2f444745087c3c51fd6042a0e25f42315ab0`
- `Linux >= 6.12.23 < 6.12.88`
- `Linux >= 6.13.11 < 6.14`
- `Linux 6.14`

## Remediation

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