---
id: CVE-2026-89645
title: >-
  kernel: btrfs: drop recovered reloc root refs on recovery failure
  (CVE-2026-89645)
summary: >-
  A flaw was found in the btrfs file system in the Linux kernel. During
  relocation recovery, if an error occurs, such as a memory allocation failure,
  the system may not properly drop references to relocation roots. 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-911
vendor: Red Hat
product: Red Hat Enterprise Linux 10
affected:
  - enterprise_linux 10
  - enterprise_linux 6
published: '2026-09-11'
updated: '2026-09-18'
sourceUpdated: '2026-09-18T22:07:40+00:00'
source: CSAF
sourceUrl: 'https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89645.json'
references:
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89645.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-89645'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2532260'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-89645'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-89645'
  - url: >-
      https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89645.mbox
  - url: 'https://git.kernel.org/stable/c/2256d6dc5b88841a8a8b4fd9a9f04730705fb6fd'
  - url: 'https://git.kernel.org/stable/c/4d43107e807bcd92621106b07f5011411c6341a8'
  - url: 'https://git.kernel.org/stable/c/6d8ba4572922e336f0b59a80751b018e1e135164'
  - url: 'https://git.kernel.org/stable/c/8a64baeb5bbb706b83d2235c1e39f5b77183817f'
tags:
  - csaf
  - vex
  - red-hat
  - cve.org
epss: 0.00225
epssPercentile: 0.13374
ingestedAt: '2026-09-14T11:11:19.885Z'
---

## Overview

A flaw was found in the btrfs file system in the Linux kernel. During relocation recovery, if an error occurs, such as a memory allocation failure, the system may not properly drop references to relocation roots. This oversight can lead to resource exhaustion, potentially allowing a local attacker to cause a denial of service (DoS) by making the system unresponsive or unstable.

## Vendor advisories

- **Red Hat VEX** · Low · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6 · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 10 · updated 2026-09-18 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89645.json)

**kernel: btrfs: drop recovered reloc root refs on recovery failure** — rated Low by Red Hat. Released 2026-09-11, updated 2026-09-18.

Affected:

- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 6

No fix planned:

- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 10

Not affected:

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

## Remediation

Out of support scope