---
id: CVE-2026-72310
title: 'smb: client: fix overflow in passthrough ioctl bounds check'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  smb: client: fix overflow in passthrough ioctl bounds check

  smb2_ioctl_query_info() validates the PASSTHRU_FSCTL response payload
  before copying it to userspace.

  The …
severity: high
cvss: 8.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 2b1116bbe898aefdf584838448c6869f69851e0f <
    175357ee0c596cb82054650dfa32fda51ad35aaa
  - >-
    Linux >= 2b1116bbe898aefdf584838448c6869f69851e0f <
    dbd126539c098dba3159ce7d34b10b2daddcbd0f
  - >-
    Linux >= 2b1116bbe898aefdf584838448c6869f69851e0f <
    63feb687e89a3a52a31e6e01764117cc500f1974
  - >-
    Linux >= 2b1116bbe898aefdf584838448c6869f69851e0f <
    160045fc943f6c46b227644261252c8a22b8a87a
  - >-
    Linux >= 2b1116bbe898aefdf584838448c6869f69851e0f <
    b30771b69eafae750afb7385fbcc3d77ed3f3670
  - >-
    Linux >= 2b1116bbe898aefdf584838448c6869f69851e0f <
    1627e7d5c9b09721a141d07cedb178882f1ded67
  - >-
    Linux >= 2b1116bbe898aefdf584838448c6869f69851e0f <
    1a638c55f2db6cb2296e5e3138015dd8fd9d4aa9
  - >-
    Linux >= 2b1116bbe898aefdf584838448c6869f69851e0f <
    a4f27ad055392fa164f5649e89a3637b033c5fcc
  - Linux 2005c32ec99ee2490e8131b3953f3f212009ffea
  - Linux >= 5.4.69 < 5.5
  - Linux 5.5
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-10-16T18:46:23.070703Z'
published: '2026-08-15'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T18:55:16.690Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-72310'
references:
  - url: 'https://git.kernel.org/stable/c/175357ee0c596cb82054650dfa32fda51ad35aaa'
  - url: 'https://git.kernel.org/stable/c/dbd126539c098dba3159ce7d34b10b2daddcbd0f'
  - url: 'https://git.kernel.org/stable/c/63feb687e89a3a52a31e6e01764117cc500f1974'
  - url: 'https://git.kernel.org/stable/c/160045fc943f6c46b227644261252c8a22b8a87a'
  - url: 'https://git.kernel.org/stable/c/b30771b69eafae750afb7385fbcc3d77ed3f3670'
  - url: 'https://git.kernel.org/stable/c/1627e7d5c9b09721a141d07cedb178882f1ded67'
  - url: 'https://git.kernel.org/stable/c/1a638c55f2db6cb2296e5e3138015dd8fd9d4aa9'
  - url: 'https://git.kernel.org/stable/c/a4f27ad055392fa164f5649e89a3637b033c5fcc'
tags:
  - cve.org
epss: 0.00643
epssPercentile: 0.49771
ingestedAt: '2026-10-16T19:46:24.410Z'
---

## Overview

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

smb: client: fix overflow in passthrough ioctl bounds check

smb2_ioctl_query_info() validates the PASSTHRU_FSCTL response payload
before copying it to userspace.

The payload offset and length both come from 32-bit fields. The bounds
check currently adds OutputOffset and qi.input_buffer_length directly, so
the addition can wrap in 32-bit arithmetic before the result is compared
against the response buffer length.

A malicious server can use a large OutputOffset and a small OutputCount
to make the wrapped sum pass the bounds check. The later copy_to_user()
then reads from io_rsp + OutputOffset, outside the response buffer.

Use size_add() for the offset plus length check so overflow is treated as
out of bounds.

## Affected

- `Linux >= 2b1116bbe898aefdf584838448c6869f69851e0f < 175357ee0c596cb82054650dfa32fda51ad35aaa`
- `Linux >= 2b1116bbe898aefdf584838448c6869f69851e0f < dbd126539c098dba3159ce7d34b10b2daddcbd0f`
- `Linux >= 2b1116bbe898aefdf584838448c6869f69851e0f < 63feb687e89a3a52a31e6e01764117cc500f1974`
- `Linux >= 2b1116bbe898aefdf584838448c6869f69851e0f < 160045fc943f6c46b227644261252c8a22b8a87a`
- `Linux >= 2b1116bbe898aefdf584838448c6869f69851e0f < b30771b69eafae750afb7385fbcc3d77ed3f3670`
- `Linux >= 2b1116bbe898aefdf584838448c6869f69851e0f < 1627e7d5c9b09721a141d07cedb178882f1ded67`
- `Linux >= 2b1116bbe898aefdf584838448c6869f69851e0f < 1a638c55f2db6cb2296e5e3138015dd8fd9d4aa9`
- `Linux >= 2b1116bbe898aefdf584838448c6869f69851e0f < a4f27ad055392fa164f5649e89a3637b033c5fcc`
- `Linux 2005c32ec99ee2490e8131b3953f3f212009ffea`
- `Linux >= 5.4.69 < 5.5`
- `Linux 5.5`

## Remediation

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