---
id: CVE-2025-21795
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  NFSD: fix hang in nfsd4_shutdown_callback

  If nfs4_client is in courtesy state then there is no point to send
  the callback
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  NFSD: fix hang in nfsd4_shutdown_callback

  If nfs4_client is in courtesy state then there is no point to send
  the callback. This causes nfsd4_shutdown_callback to hang …
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'
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 5.10.220, < 5.10.235'
  - 'linux_kernel >= 5.15.154, < 5.15.179'
  - 'linux_kernel >= 5.19, < 6.1.129'
  - 'linux_kernel >= 6.2, < 6.6.79'
  - 'linux_kernel >= 6.7, < 6.12.16'
  - 'linux_kernel >= 6.13, < 6.13.4'
  - linux_kernel = 6.14
patched:
  - linux_kernel 6.13.4
published: '2025-02-27'
updated: '2026-07-14'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-21795'
references:
  - url: 'https://git.kernel.org/stable/c/036ac2778f7b28885814c6fbc07e156ad1624d03'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/23ad7797c74cd8f7f90617f1e59a8703e2b43908'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/38d345f612503b850c2973e5a879f88e441b34d7'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/abed68027ea3ab893ac85cc46a00e2e64a324239'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/cedfbb92cf97a6bff3d25633001d9c44442ee854'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/e88d2451cd42e025465d6b51fd716a47b0b3800d'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/efa8a261c575f816c7e79a87aeb3ef8a0bd6b221'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-019113.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-082556.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-265688.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
  - cve.org
epss: 0.00643
epssPercentile: 0.49474
ingestedAt: '2026-07-14T13:36:55.735Z'
---

## Overview

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

NFSD: fix hang in nfsd4_shutdown_callback

If nfs4_client is in courtesy state then there is no point to send
the callback. This causes nfsd4_shutdown_callback to hang since
cl_cb_inflight is not 0. This hang lasts about 15 minutes until TCP
notifies NFSD that the connection was dropped.

This patch modifies nfsd4_run_cb_work to skip the RPC call if
nfs4_client is in courtesy state.

## Affected

- `linux_kernel >= 5.10.220, < 5.10.235`
- `linux_kernel >= 5.15.154, < 5.15.179`
- `linux_kernel >= 5.19, < 6.1.129`
- `linux_kernel >= 6.2, < 6.6.79`
- `linux_kernel >= 6.7, < 6.12.16`
- `linux_kernel >= 6.13, < 6.13.4`
- `linux_kernel = 6.14`

## Remediation

Upgrade past the affected range:

- `linux_kernel 6.13.4`