---
id: CVE-2026-89630
title: >-
  kernel: smb: client: restore the data_offset bound in is_valid_oplock_break()
  (CVE-2026-89630)
summary: >-
  A flaw was found in the Linux kernel's Server Message Block (SMB) client. An
  incorrect calculation of the `data_offset` bound in the
  `is_valid_oplock_break()` function can lead to a read overflow. This
  vulnerability allows a malicious SMB …
severity: high
cvss: 7
cvssVector: 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'
cvssSource: vendor
cwe: CWE-125
vendor: Red Hat
product: Red Hat Enterprise Linux 9
affected:
  - enterprise_linux 10
  - enterprise_linux 9
  - openshift_container_platform 4
published: '2026-09-11'
updated: '2026-09-14'
sourceUpdated: '2026-09-14T17:46:37+00:00'
source: CSAF
sourceUrl: 'https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89630.json'
references:
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89630.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-89630'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2532051'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-89630'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-89630'
  - url: >-
      https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89630.mbox
  - url: 'https://git.kernel.org/stable/c/5b16a1967a01ad4496a7206a87c3eb16f1df2b05'
  - url: 'https://git.kernel.org/stable/c/ba22f575de9deeae4ae0859ca4315a7698226237'
tags:
  - csaf
  - vex
  - red-hat
  - cve.org
  - score-dispute
epss: 0.00539
epssPercentile: 0.42865
scores:
  vendor: 6.3
  cna: 9.1
ingestedAt: '2026-09-14T15:23:07.474Z'
---

## Overview

A flaw was found in the Linux kernel's Server Message Block (SMB) client. An incorrect calculation of the `data_offset` bound in the `is_valid_oplock_break()` function can lead to a read overflow. This vulnerability allows a malicious SMB server to potentially trigger an out-of-bounds read, which could result in information disclosure or a denial of service.

## Vendor advisories

- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · updated 2026-09-14 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89630.json)

**kernel: smb: client: restore the data_offset bound in is_valid_oplock_break()** — rated Moderate by Red Hat. Released 2026-09-11, updated 2026-09-14.

Affected:

- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 9
- Red Hat OpenShift Container Platform 4

No fix planned:

- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 9
- Red Hat OpenShift Container Platform 4

Not affected:

- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat OpenShift Container Platform 4

## Remediation

Affected