---
id: CVE-2026-89676
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  nfsd: fix stale s2s_cp_stateids IDR entry for async COPY

  For an async COPY, nfsd4_copy() called nfs4_init_copy_state() before
  dup_copy_fields(), so the s2s_cp_stateids…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  nfsd: fix stale s2s_cp_stateids IDR entry for async COPY

  For an async COPY, nfsd4_copy() called nfs4_init_copy_state() before
  dup_copy_fields(), so the s2s_cp_stateids…
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'
cwe:
  - CWE-825
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= e0639dc5805a9d4faaa2c07ad98fa853b9529dd3 <
    7aa34ea78f74e6ef60c8112635a87fc43d57f6c9
  - >-
    Linux >= e0639dc5805a9d4faaa2c07ad98fa853b9529dd3 <
    9b4e5e9ba5ae13808b8a6d229d87c54611ba0e7a
  - >-
    Linux >= e0639dc5805a9d4faaa2c07ad98fa853b9529dd3 <
    14b978e8d05ce018d0afbeb6611833ef91713a02
  - >-
    Linux >= e0639dc5805a9d4faaa2c07ad98fa853b9529dd3 <
    d0beaee498e11880e72826026db0e9c9890fc114
  - Linux 4.20
published: '2026-09-11'
updated: '2026-09-21'
sourceUpdated: '2026-09-21T14:17:25.073'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-89676'
references:
  - url: 'https://git.kernel.org/stable/c/14b978e8d05ce018d0afbeb6611833ef91713a02'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/7aa34ea78f74e6ef60c8112635a87fc43d57f6c9'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/9b4e5e9ba5ae13808b8a6d229d87c54611ba0e7a'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/d0beaee498e11880e72826026db0e9c9890fc114'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89676.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-89676'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2532219'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-89676'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-89676'
  - url: >-
      https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89676.mbox
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
  - score-dispute
epss: 0.00463
epssPercentile: 0.39388
scores:
  nvd: 9.8
  cna: 9.8
  vendor: 7
ingestedAt: '2026-09-14T15:23:07.473Z'
---

## Overview

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

nfsd: fix stale s2s_cp_stateids IDR entry for async COPY

For an async COPY, nfsd4_copy() called nfs4_init_copy_state() before
dup_copy_fields(), so the s2s_cp_stateids IDR was pointed at
&u->copy->cp_stateid -- memory in the per-rqstp COMPOUND buffer that is
reused by the next request. dup_copy_fields() copies only the value into
async_copy, so the IDR slot dangled at the transient buffer for the whole
background copy. Any IDR walker then dereferences reused request memory:
the laundromat reads cs_type from it and, if the bytes look like an
expired NFS4_COPYNOTIFY_STID, follows into
refcount_dec()/idr_remove()/kfree() on garbage; manage_cpntf_state() has
the same exposure via idr_find().

Duplicate the fields first, then register the stateid on the stable
async_copy. result->cb_stateid is unchanged.

## 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 2026-09-21 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89676.json)