---
id: CVE-2026-89632
title: 'smb: client: fix use-before-check of ReparseDataLength in reparse_buf_ptr()'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  smb: client: fix use-before-check of ReparseDataLength in reparse_buf_ptr()

  reparse_buf_ptr() reads buf->ReparseDataLength before checking that
  count covers the full f…
severity: high
cvss: 8.2
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H'
cvssSource: cna
cwe:
  - CWE-125
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= a158bb66b1373866d9fd5997565a58a573085539 <
    b70bc592afd19732e2e4563300ebe8f974280365
  - >-
    Linux >= 67ec9949b0dfe78c99e110dd975eb7dc5645630c <
    711cf71300d7992f450600df8864917d3538679f
  - >-
    Linux >= 67ec9949b0dfe78c99e110dd975eb7dc5645630c <
    05f78e6cf34ea3a285053bd5999e08e8ac298bd5
  - Linux >= 6.6.32 < 6.6.160
  - Linux 6.8
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-10-16T19:24:44.423758Z'
published: '2026-09-11'
updated: '2026-10-21'
sourceUpdated: '2026-10-21T12:48:04.460Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-89632'
references:
  - url: 'https://git.kernel.org/stable/c/b70bc592afd19732e2e4563300ebe8f974280365'
  - url: 'https://git.kernel.org/stable/c/711cf71300d7992f450600df8864917d3538679f'
  - url: 'https://git.kernel.org/stable/c/05f78e6cf34ea3a285053bd5999e08e8ac298bd5'
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89632.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-89632'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2532415'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-89632'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-89632'
  - url: >-
      https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89632.mbox
tags:
  - cve.org
  - csaf
  - vex
  - red-hat
epss: 0.00551
epssPercentile: 0.45887
scores:
  cna: 8.2
  vendor: 7
ingestedAt: '2026-09-14T15:23:07.473Z'
---

## Overview

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

smb: client: fix use-before-check of ReparseDataLength in reparse_buf_ptr()

reparse_buf_ptr() reads buf->ReparseDataLength before checking that
count covers the full fixed header:

    buf = (struct reparse_data_buffer *)((u8 *)io + off);
    len = sizeof(*buf);                          /* 8 bytes */
    rdlen = le16_to_cpu(buf->ReparseDataLength); /* offset 4, 2 bytes */

    if (count < len || count < rdlen + len)      /* check comes after */

struct reparse_data_buffer has ReparseDataLength at offset 4.  If a
server returns OutputCount < 6, the read at offset 4-5 reaches past
the end of the received data.  The off+count bounds against iov_len
were already validated, but that does not protect against count being
smaller than sizeof(*buf).

Split the check: verify count >= sizeof(*buf) before reading
ReparseDataLength, then verify count covers the data region.

## Affected

- `Linux >= a158bb66b1373866d9fd5997565a58a573085539 < b70bc592afd19732e2e4563300ebe8f974280365`
- `Linux >= 67ec9949b0dfe78c99e110dd975eb7dc5645630c < 711cf71300d7992f450600df8864917d3538679f`
- `Linux >= 67ec9949b0dfe78c99e110dd975eb7dc5645630c < 05f78e6cf34ea3a285053bd5999e08e8ac298bd5`
- `Linux >= 6.6.32 < 6.6.160`
- `Linux 6.8`

## Remediation

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

## Vendor advisories

- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · updated 2026-09-18 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89632.json)