---
id: CVE-2026-89768
title: 'kernel: fs: fix user path of nested backing files (CVE-2026-89768)'
summary: >-
  A flaw was found in the Linux kernel's filesystem (fs) component. When using
  nested overlay filesystems (overlayfs), a local user could exploit an issue
  where the backing_file_open() function incorrectly derives the path for mapped
  files. …
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-41
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: '2026-09-21'
sourceUpdated: '2026-09-21T19:34:57+00:00'
source: CSAF
sourceUrl: 'https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89768.json'
references:
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89768.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-89768'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2532171'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-89768'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-89768'
  - url: >-
      https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89768.mbox
  - url: 'https://git.kernel.org/stable/c/88c927a63dc717b6d46b20fe13ea713916e49089'
  - url: 'https://git.kernel.org/stable/c/a35cc21355734e1acb89973d9be90ca8e4c3ed2f'
  - url: 'https://git.kernel.org/stable/c/c03114634d342648bd34910aa8fb88007e92cc3c'
  - url: 'https://git.kernel.org/stable/c/f2381b546e7e6a35c9fcee0d0ccb6c042a9aeb5d'
tags:
  - csaf
  - vex
  - red-hat
  - cve.org
epss: 0.00186
epssPercentile: 0.08467
ingestedAt: '2026-09-14T11:11:19.884Z'
---

## Overview

A flaw was found in the Linux kernel's filesystem (fs) component. When using nested overlay filesystems (overlayfs), a local user could exploit an issue where the backing_file_open() function incorrectly derives the path for mapped files. This vulnerability leads to information disclosure, as files mapped through a nested overlayfs display an incorrect path in /proc/<pid>/maps and perf/ftrace mmap records.

## 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 2026-09-21 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89768.json)

**kernel: fs: fix user path of nested backing files** — rated Moderate by Red Hat. Released 2026-09-11, updated 2026-09-21.

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

Fix deferred