---
id: CVE-2026-89714
title: 'NFS: fix delegation_hash_table leak when nfs4_server_common_setup() fails'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  NFS: fix delegation_hash_table leak when nfs4_server_common_setup() fails

  nfs4_server_common_setup() allocates server->delegation_hash_table
  first, but server->destroy…
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-772
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= f5b3108e6a14418b120a3c38ca589b8d6cf87627 <
    f3adf1643517357221422c05986d6de5df7b9913
  - >-
    Linux >= f5b3108e6a14418b120a3c38ca589b8d6cf87627 <
    0fd2b9687dae36be5b84eab39b4c627bb7ab33b3
  - >-
    Linux >= f5b3108e6a14418b120a3c38ca589b8d6cf87627 <
    2092f5b38f88be306140c77aeeeb43fc1adacacc
  - Linux 6.17
published: '2026-09-11'
updated: '2026-10-19'
sourceUpdated: '2026-10-19T08:51:27.182Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-89714'
references:
  - url: 'https://git.kernel.org/stable/c/f3adf1643517357221422c05986d6de5df7b9913'
  - url: 'https://git.kernel.org/stable/c/0fd2b9687dae36be5b84eab39b4c627bb7ab33b3'
  - url: 'https://git.kernel.org/stable/c/2092f5b38f88be306140c77aeeeb43fc1adacacc'
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89714.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-89714'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2532288'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-89714'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-89714'
  - url: >-
      https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89714.mbox
tags:
  - cve.org
  - csaf
  - vex
  - red-hat
epss: 0.00206
epssPercentile: 0.10612
ingestedAt: '2026-09-14T11:11:19.885Z'
---

## Overview

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

NFS: fix delegation_hash_table leak when nfs4_server_common_setup() fails

nfs4_server_common_setup() allocates server->delegation_hash_table
first, but server->destroy - the only path that frees the table via
nfs4_destroy_server() - is not assigned until the very end of the
function. If any intermediate step fails (the is_ds_only_client()
check, nfs4_init_session(), nfs4_get_rootfh(), or nfs_probe_server()),
the function returns with server->destroy still NULL, so the caller's
nfs_free_server() skips the destroy callback and the hash table is
leaked (4 KiB per attempt with the default delegation watermark).

This is trivially reachable from userspace: every failed NFSv4 mount
leaks one allocation. A client that persistently retries a mount that
cannot succeed leaks kernel memory without bound. Observed in
production where a Longhorn backup poller retried mount.nfs4 against
an NFSv3-only server roughly 10 times per second, leaking ~3.4 GiB of
unreclaimable slab (kmalloc-rnd-13-4k) per day; the node accumulated
12 GiB of leaked slab before the source was identified via the
kmem:kmalloc tracepoint (call_site=nfs4_delegation_hash_alloc).

Reproducer:

  # server exports NFSv3 only (or export path absent for v4)
  while :; do mount -t nfs4 <server>:/missing /mnt; done
  # watch SUnreclaim in /proc/meminfo grow 4 KiB per iteration

Free the table on the error paths between the allocation and the
assignment of server->destroy.

## Affected

- `Linux >= f5b3108e6a14418b120a3c38ca589b8d6cf87627 < f3adf1643517357221422c05986d6de5df7b9913`
- `Linux >= f5b3108e6a14418b120a3c38ca589b8d6cf87627 < 0fd2b9687dae36be5b84eab39b4c627bb7ab33b3`
- `Linux >= f5b3108e6a14418b120a3c38ca589b8d6cf87627 < 2092f5b38f88be306140c77aeeeb43fc1adacacc`
- `Linux 6.17`

## Remediation

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

## Vendor advisories

- **Red Hat VEX** · Low · affected: Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat OpenShift Container Platform 4 · updated 2026-09-21 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89714.json)