---
id: CVE-2026-89653
title: >-
  kernel: ceph: reject export_targets ranks >= CEPH_MAX_MDS in mdsmap decode
  (CVE-2026-89653)
summary: >-
  A flaw was found in the Linux kernel's Ceph filesystem. This vulnerability
  occurs when a malicious or malformed MDSMap export_targets entry, controlled
  by a monitor, contains a rank value that exceeds the maximum allowed
  (CEPH_MAX_MDS) dur…
severity: high
cvss: 8.1
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H'
cvssSource: vendor
cwe: CWE-787
vendor: Red Hat
product: Red Hat Enterprise Linux 9
affected:
  - enterprise_linux 10
  - enterprise_linux 8
  - enterprise_linux 9
  - openshift_container_platform 4
published: '2026-09-11'
updated: '2026-09-16'
sourceUpdated: '2026-09-16T20:41:51+00:00'
source: CSAF
sourceUrl: 'https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89653.json'
references:
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89653.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-89653'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2532386'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-89653'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-89653'
  - url: >-
      https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89653.mbox
  - url: 'https://git.kernel.org/stable/c/3740c88ca9cb2210a8dbdd55ea4cec119fbe86fe'
  - url: 'https://git.kernel.org/stable/c/8c823bbab3c24e657469a84db96902ba82d4e8bb'
  - url: 'https://git.kernel.org/stable/c/c4addccd05bacbef2144b4db14853d0308a218ac'
  - url: 'https://git.kernel.org/stable/c/736adee11af36e407ed902264f8b2fb5cf94b62f'
  - url: 'https://git.kernel.org/stable/c/4d298880f82c42383b36946bafde7ccf4d804c9b'
  - url: 'https://git.kernel.org/stable/c/96c3f5fbb0d5386e7111426f047f98cec4586674'
  - url: 'https://git.kernel.org/stable/c/aedc9053d909508a5f56c3f49f885fc030df4730'
tags:
  - csaf
  - vex
  - red-hat
  - cve.org
  - score-dispute
epss: 0.00509
epssPercentile: 0.42467
scores:
  vendor: 7
  cna: 9.8
ingestedAt: '2026-09-14T15:23:07.450Z'
---

## Overview

A flaw was found in the Linux kernel's Ceph filesystem. This vulnerability occurs when a malicious or malformed MDSMap export_targets entry, controlled by a monitor, contains a rank value that exceeds the maximum allowed (CEPH_MAX_MDS) during the decoding process. This can lead to an out-of-bounds write, where the system attempts to write data beyond its designated memory area. Such an issue could result in a denial of service (DoS), making the system unresponsive or unstable.

## Vendor advisories

- **Red Hat VEX** · Important · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · updated 2026-09-16 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89653.json)

**kernel: ceph: reject export_targets ranks >= CEPH_MAX_MDS in mdsmap decode** — rated Important by Red Hat. Released 2026-09-11, updated 2026-09-16.

Affected:

- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
- Red Hat OpenShift Container Platform 4

No fix planned:

- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
- Red Hat OpenShift Container Platform 4

Not affected:

- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7

## Remediation

Affected