---
id: CVE-2026-89990
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ceph: lock mutex in ceph_mds_check_access()

  MDS session OPEN handling replaces mdsc->s_cap_auths under
  mdsc->mutex, freeing the previous array and its strings.

  ceph_m…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ceph: lock mutex in ceph_mds_check_access()

  MDS session OPEN handling replaces mdsc->s_cap_auths under
  mdsc->mutex, freeing the previous array and its strings.

  ceph_m…
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'
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 596afb0b8933ba6ed7227adcc538db26feb25c74 <
    729c1ff670ece6f3d4b1738365a0b2f90d487523
  - >-
    Linux >= 596afb0b8933ba6ed7227adcc538db26feb25c74 <
    ca5bfea2045ef2eb3305cf2a9d8da549b76c37d3
  - >-
    Linux >= 596afb0b8933ba6ed7227adcc538db26feb25c74 <
    df1a97d5313fccadb08390306d49b194fb027392
  - >-
    Linux >= 596afb0b8933ba6ed7227adcc538db26feb25c74 <
    a61c6ae1dae2611082b831b4aaa780878099c012
  - Linux 6.10
published: '2026-09-16'
updated: '2026-09-16'
sourceUpdated: '2026-09-16T15:18:22.800'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-89990'
references:
  - url: 'https://git.kernel.org/stable/c/729c1ff670ece6f3d4b1738365a0b2f90d487523'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/a61c6ae1dae2611082b831b4aaa780878099c012'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/ca5bfea2045ef2eb3305cf2a9d8da549b76c37d3'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/df1a97d5313fccadb08390306d49b194fb027392'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-16T10:53:53.949Z'
epss: 0.00608
epssPercentile: 0.47807
---

## Overview

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

ceph: lock mutex in ceph_mds_check_access()

MDS session OPEN handling replaces mdsc->s_cap_auths under
mdsc->mutex, freeing the previous array and its strings.

ceph_mds_check_access() traverses this array without holding the
mutex.  A concurrent session reopen can therefore free the array while
it is being inspected, resulting in a use-after-free like this:

  Unable to handle kernel paging request at virtual address 003aaad64b2c8bb9
  [...]
  Internal error: Oops: 0000000096000004 [#1]  SMP
  Modules linked in:
  CPU: 56 UID: 2953037534 PID: 1253231 Comm: php-cgi8.4 Not tainted 6.18.45-i2-ampere #1146 NONE
  [..]
  pc : ceph_mds_check_access+0xd4/0x550
  lr : ceph_mds_check_access+0xc8/0x550
  [...]
  Call trace:
   ceph_mds_check_access+0xd4/0x550 (P)
   ceph_atomic_open+0x138/0xbe8
   path_openat+0xa24/0xfa8
   do_filp_open+0x94/0x158
   do_sys_openat2+0x88/0xf8

## Remediation

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