---
id: CVE-2026-89653
title: 'ceph: reject export_targets ranks >= CEPH_MAX_MDS in mdsmap decode'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ceph: reject export_targets ranks >= CEPH_MAX_MDS in mdsmap decode

  MDSMap export_targets entries are monitor controlled. check_new_map()
  uses each entry as a bit numbe…
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cvssSource: cna
cwe:
  - CWE-787
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= d517b3983dd3106ca92d6c5d0d09415a4a09481c <
    3740c88ca9cb2210a8dbdd55ea4cec119fbe86fe
  - >-
    Linux >= d517b3983dd3106ca92d6c5d0d09415a4a09481c <
    8c823bbab3c24e657469a84db96902ba82d4e8bb
  - >-
    Linux >= d517b3983dd3106ca92d6c5d0d09415a4a09481c <
    c4addccd05bacbef2144b4db14853d0308a218ac
  - >-
    Linux >= d517b3983dd3106ca92d6c5d0d09415a4a09481c <
    736adee11af36e407ed902264f8b2fb5cf94b62f
  - >-
    Linux >= d517b3983dd3106ca92d6c5d0d09415a4a09481c <
    4d298880f82c42383b36946bafde7ccf4d804c9b
  - >-
    Linux >= d517b3983dd3106ca92d6c5d0d09415a4a09481c <
    96c3f5fbb0d5386e7111426f047f98cec4586674
  - >-
    Linux >= d517b3983dd3106ca92d6c5d0d09415a4a09481c <
    aedc9053d909508a5f56c3f49f885fc030df4730
  - Linux 5.15
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: total
  timestamp: '2026-10-16T19:25:22.176850Z'
published: '2026-09-11'
updated: '2026-10-19'
sourceUpdated: '2026-10-19T08:50:24.862Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-89653'
references:
  - 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'
  - 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
tags:
  - cve.org
  - csaf
  - vex
  - red-hat
epss: 0.00502
epssPercentile: 0.42784
scores:
  cna: 9.8
  vendor: 8.1
ingestedAt: '2026-09-14T15:23:07.450Z'
---

## Overview

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

ceph: reject export_targets ranks >= CEPH_MAX_MDS in mdsmap decode

MDSMap export_targets entries are monitor controlled. check_new_map()
uses each entry as a bit number in a fixed stack bitmap, so a rank
outside the protocol namespace can make set_bit() write past the end of
the array.

Reject ranks outside CEPH_MAX_MDS while decoding the map. Do not
validate against possible_max_rank here because maps may legitimately
reference ranks beyond a temporarily reduced max_mds.

## Affected

- `Linux >= d517b3983dd3106ca92d6c5d0d09415a4a09481c < 3740c88ca9cb2210a8dbdd55ea4cec119fbe86fe`
- `Linux >= d517b3983dd3106ca92d6c5d0d09415a4a09481c < 8c823bbab3c24e657469a84db96902ba82d4e8bb`
- `Linux >= d517b3983dd3106ca92d6c5d0d09415a4a09481c < c4addccd05bacbef2144b4db14853d0308a218ac`
- `Linux >= d517b3983dd3106ca92d6c5d0d09415a4a09481c < 736adee11af36e407ed902264f8b2fb5cf94b62f`
- `Linux >= d517b3983dd3106ca92d6c5d0d09415a4a09481c < 4d298880f82c42383b36946bafde7ccf4d804c9b`
- `Linux >= d517b3983dd3106ca92d6c5d0d09415a4a09481c < 96c3f5fbb0d5386e7111426f047f98cec4586674`
- `Linux >= d517b3983dd3106ca92d6c5d0d09415a4a09481c < aedc9053d909508a5f56c3f49f885fc030df4730`
- `Linux 5.15`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## 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 2026-10-05 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89653.json)