---
id: CVE-2026-89493
title: >-
  kernel: ocfs2: validate rl_used against rl_count in refcount block validator
  (CVE-2026-89493)
summary: >-
  A flaw was found in the Linux kernel's ocfs2 component. A local attacker with
  CAP_SYS_ADMIN privileges could exploit this by mounting a crafted or corrupted
  ocfs2 image, or by performing a raw write to the block device backing an
  already-m…
severity: medium
cvss: 5.5
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'
cvssSource: vendor
cwe: CWE-787
vendor: Red Hat
product: Linux
affected:
  - >-
    Linux >= f2c870e3b12e38da6d9b5b17c4c8ae56a0ed68e4 <
    f882e9e32d017a6569b2996c63ba3864717788e6
  - >-
    Linux >= f2c870e3b12e38da6d9b5b17c4c8ae56a0ed68e4 <
    5593b63028cb43a6cda75a65ce1db95f00ea6857
  - >-
    Linux >= f2c870e3b12e38da6d9b5b17c4c8ae56a0ed68e4 <
    c8b02f4ee91e757b3fff556c7168b24b7ae55132
  - >-
    Linux >= f2c870e3b12e38da6d9b5b17c4c8ae56a0ed68e4 <
    97584e93fc49a2d59252ac60467e9279f11b1b5b
  - >-
    Linux >= f2c870e3b12e38da6d9b5b17c4c8ae56a0ed68e4 <
    af56e90cb546cb0c47bef059335365283f61d6a4
  - >-
    Linux >= f2c870e3b12e38da6d9b5b17c4c8ae56a0ed68e4 <
    0761d2c9494424469a0d30a9da3496ca010b0b2d
  - >-
    Linux >= f2c870e3b12e38da6d9b5b17c4c8ae56a0ed68e4 <
    04ead708e13ddcb9c39319cbe02a18cef99cb823
  - >-
    Linux >= f2c870e3b12e38da6d9b5b17c4c8ae56a0ed68e4 <
    4ca62df6bc0708947b48da3f6a712ecb8e73929c
  - Linux 2.6.32
published: '2026-09-11'
updated: '2026-09-18'
sourceUpdated: '2026-09-18T11:28:50+00:00'
source: CSAF
sourceUrl: 'https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89493.json'
references:
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89493.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-89493'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2532390'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-89493'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-89493'
  - url: >-
      https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89493.mbox
  - url: 'https://git.kernel.org/stable/c/f882e9e32d017a6569b2996c63ba3864717788e6'
  - url: 'https://git.kernel.org/stable/c/5593b63028cb43a6cda75a65ce1db95f00ea6857'
  - url: 'https://git.kernel.org/stable/c/c8b02f4ee91e757b3fff556c7168b24b7ae55132'
  - url: 'https://git.kernel.org/stable/c/97584e93fc49a2d59252ac60467e9279f11b1b5b'
  - url: 'https://git.kernel.org/stable/c/af56e90cb546cb0c47bef059335365283f61d6a4'
  - url: 'https://git.kernel.org/stable/c/0761d2c9494424469a0d30a9da3496ca010b0b2d'
  - url: 'https://git.kernel.org/stable/c/04ead708e13ddcb9c39319cbe02a18cef99cb823'
  - url: 'https://git.kernel.org/stable/c/4ca62df6bc0708947b48da3f6a712ecb8e73929c'
tags:
  - csaf
  - vex
  - red-hat
  - cve.org
  - score-dispute
epss: 0.00678
epssPercentile: 0.50276
scores:
  vendor: 5.5
  cna: 8.8
ingestedAt: '2026-09-14T15:23:07.452Z'
---

## Overview

A flaw was found in the Linux kernel's ocfs2 component. A local attacker with CAP_SYS_ADMIN privileges could exploit this by mounting a crafted or corrupted ocfs2 image, or by performing a raw write to the block device backing an already-mounted ocfs2 filesystem. This vulnerability arises from insufficient validation of rl_used against rl_count in the refcount block validator, allowing an out-of-bounds read and write operation. Successful exploitation could lead to memory corruption and system instability.

## Vendor advisories

- **Red Hat VEX** · Moderate · updated 2026-09-18 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89493.json)

**kernel: ocfs2: validate rl_used against rl_count in refcount block validator** — rated Moderate by Red Hat. Released 2026-09-11, updated 2026-09-18.

Not affected:

- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
- Red Hat OpenShift Container Platform 4

## Remediation

Refer to the advisory for fix availability.