---
id: CVE-2026-89639
title: >-
  kernel: cifs: use cifs_invalidate_cache() in cifs_do_truncate() for O_TRUNC
  (CVE-2026-89639)
summary: >-
  A flaw was found in the Linux kernel's Common Internet File System (CIFS)
  implementation. When a file is truncated, the `cifs_do_truncate()` function
  does not properly invalidate the file system cache (fscache). This oversight
  can lead to …
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-524
vendor: Red Hat
product: Red Hat Enterprise Linux 10
affected:
  - enterprise_linux 10
published: '2026-09-11'
updated: '2026-09-16'
sourceUpdated: '2026-09-16T14:15:00+00:00'
source: CSAF
sourceUrl: 'https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89639.json'
references:
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89639.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-89639'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2532382'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-89639'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-89639'
  - url: >-
      https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89639.mbox
  - url: 'https://git.kernel.org/stable/c/364b183230586a62660a7280c1eb20138338eeb5'
  - url: 'https://git.kernel.org/stable/c/81fc3868a7f726980ff845c1d0d271051e5f0f45'
  - url: 'https://git.kernel.org/stable/c/8b9b10fe5b8b492b27b9f4546742ea541a650213'
tags:
  - csaf
  - vex
  - red-hat
  - cve.org
  - score-dispute
epss: 0.0017
epssPercentile: 0.05562
scores:
  vendor: 3.3
  cna: 7.1
ingestedAt: '2026-09-14T15:23:07.473Z'
---

## Overview

A flaw was found in the Linux kernel's Common Internet File System (CIFS) implementation. When a file is truncated, the `cifs_do_truncate()` function does not properly invalidate the file system cache (fscache). This oversight can lead to stale cached data being served to users, potentially resulting in information disclosure or data inconsistency.

## Vendor advisories

- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10 · no fix planned: Red Hat Enterprise Linux 10 · updated 2026-09-16 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89639.json)

**kernel: cifs: use cifs_invalidate_cache() in cifs_do_truncate() for O_TRUNC** — rated Moderate by Red Hat. Released 2026-09-11, updated 2026-09-16.

Affected:

- Red Hat Enterprise Linux 10

No fix planned:

- Red Hat Enterprise Linux 10

Not affected:

- 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

Fix deferred