---
id: CVE-2026-89639
title: 'cifs: use cifs_invalidate_cache() in cifs_do_truncate() for O_TRUNC'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  cifs: use cifs_invalidate_cache() in cifs_do_truncate() for O_TRUNC

  cifs_do_truncate() is invoked from cifs_open() without i_rwsem, so it
  cannot use cifs_resize_file_l…
severity: high
cvss: 7.1
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N'
cvssSource: cna
cwe:
  - CWE-524
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= efbcecdecefc26fa062c0e8210533ccad7d6bd4a <
    8b9b10fe5b8b492b27b9f4546742ea541a650213
  - >-
    Linux >= fa724e235cfdb0fb0bb427d0f9dfe864ae27403e <
    81fc3868a7f726980ff845c1d0d271051e5f0f45
  - >-
    Linux >= fa724e235cfdb0fb0bb427d0f9dfe864ae27403e <
    364b183230586a62660a7280c1eb20138338eeb5
  - Linux 6838bcac954487cc0a3c8a4ee1b3a3a30e244dc9
  - Linux 75640976cf474eb41682a13f2dbe9534ac26ca50
  - Linux 3513f3931c579ba2a715784c6dedc59e0d9282ee
  - Linux >= 6.18.44 < 6.18.50
  - Linux >= 6.12.105 < 6.13
  - Linux >= 7.1.8 < 7.2
  - Linux 7.2
published: '2026-09-11'
updated: '2026-10-19'
sourceUpdated: '2026-10-19T08:50:11.190Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-89639'
references:
  - url: 'https://git.kernel.org/stable/c/8b9b10fe5b8b492b27b9f4546742ea541a650213'
  - url: 'https://git.kernel.org/stable/c/81fc3868a7f726980ff845c1d0d271051e5f0f45'
  - url: 'https://git.kernel.org/stable/c/364b183230586a62660a7280c1eb20138338eeb5'
  - 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
tags:
  - cve.org
  - csaf
  - vex
  - red-hat
epss: 0.0017
epssPercentile: 0.06302
scores:
  cna: 7.1
  vendor: 5.5
ingestedAt: '2026-09-14T15:23:07.473Z'
---

## Overview

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

cifs: use cifs_invalidate_cache() in cifs_do_truncate() for O_TRUNC

cifs_do_truncate() is invoked from cifs_open() without i_rwsem, so it
cannot use cifs_resize_file_locked() to perform a proper fscache cookie
resize.  Instead, add cifs_invalidate_cache() after cifs_setsize().

cifs_invalidate_cache() calls fscache_invalidate(), which works without
holding i_rwsem: it unconditionally increments inval_counter and sets
FSCACHE_COOKIE_NO_DATA_TO_READ, ensuring that stale cached data is not
served once the cookie is later activated by fscache_use_cookie().
Truncation to zero leaves no valid cached data, making invalidation the
correct semantic here.

## Affected

- `Linux >= efbcecdecefc26fa062c0e8210533ccad7d6bd4a < 8b9b10fe5b8b492b27b9f4546742ea541a650213`
- `Linux >= fa724e235cfdb0fb0bb427d0f9dfe864ae27403e < 81fc3868a7f726980ff845c1d0d271051e5f0f45`
- `Linux >= fa724e235cfdb0fb0bb427d0f9dfe864ae27403e < 364b183230586a62660a7280c1eb20138338eeb5`
- `Linux 6838bcac954487cc0a3c8a4ee1b3a3a30e244dc9`
- `Linux 75640976cf474eb41682a13f2dbe9534ac26ca50`
- `Linux 3513f3931c579ba2a715784c6dedc59e0d9282ee`
- `Linux >= 6.18.44 < 6.18.50`
- `Linux >= 6.12.105 < 6.13`
- `Linux >= 7.1.8 < 7.2`
- `Linux 7.2`

## 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 · 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)