---
id: CVE-2026-89718
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  zram: fix out-of-bounds access in writeback_store()

  Patch series "zram: fix stale scan bounds after reinitialization".

  Both writeback_store() and read_block_state() d…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  zram: fix out-of-bounds access in writeback_store()

  Patch series "zram: fix stale scan bounds after reinitialization".

  Both writeback_store() and read_block_state() d…
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'
cwe:
  - CWE-131
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= a939888ec38bf1f33e4a903056677e92a4844244 <
    4d82d60178b02797dbe529e01ac211b26670c49f
  - >-
    Linux >= a939888ec38bf1f33e4a903056677e92a4844244 <
    07a82a66f8c1894d92e51d97542c32ebf2c51b09
  - >-
    Linux >= a939888ec38bf1f33e4a903056677e92a4844244 <
    894913e2d35c46ff19a77530907771ae57862b96
  - Linux 5.0
published: '2026-09-11'
updated: '2026-09-21'
sourceUpdated: '2026-09-21T14:17:25.967'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-89718'
references:
  - url: 'https://git.kernel.org/stable/c/07a82a66f8c1894d92e51d97542c32ebf2c51b09'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/4d82d60178b02797dbe529e01ac211b26670c49f'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/894913e2d35c46ff19a77530907771ae57862b96'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89718.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-89718'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2532376'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-89718'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-89718'
  - url: >-
      https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89718.mbox
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
epss: 0.00166
epssPercentile: 0.06247
cvssSource: vendor
ingestedAt: '2026-09-14T11:11:19.885Z'
---

## Overview

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

zram: fix out-of-bounds access in writeback_store()

Patch series "zram: fix stale scan bounds after reinitialization".

Both writeback_store() and read_block_state() derive their table scan
bounds from zram->disksize before acquiring dev_lock.  If the device is
reset and reinitialized with a smaller disksize between that read and lock
acquisition, the bound can describe the old table while the scan operates
on the new one.  This can lead to out-of-bounds slot accesses.

Move both bound calculations under dev_lock so each bound remains
consistent with the table throughout its scan.  Keep the fixes separate
because the affected interfaces originate from different commits and can
be backported independently.


This patch (of 2):

writeback_store() calculates the table scan bounds before taking dev_lock.
A reset followed by reconfiguration with a smaller disksize can therefore
replace zram->table while writeback_store() is waiting for the lock.  Once
it acquires the lock, it sees an initialized device but scans the new
table using the old upper bound, resulting in an out-of-bounds access.

Calculate the number of pages while holding dev_lock so the scan bound
matches the table protected by the lock.

## Remediation

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

## Vendor advisories

- **Red Hat VEX** · Moderate · affected: Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat OpenShift Container Platform 4 · updated 2026-09-16 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89718.json)