---
id: CVE-2025-21955
title: 'ksmbd: prevent connection release during oplock break notification'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ksmbd: prevent connection release during oplock break notification

  ksmbd_work could be freed when after connection release.
  Increment r_count of ksmbd_conn to indicate…
severity: high
cvss: 8.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 0626e6641f6b467447c81dd7678a69c66f7746cf <
    8e6508c7ecb1802909f294827eff38f301d0c937
  - >-
    Linux >= 0626e6641f6b467447c81dd7678a69c66f7746cf <
    09aeab68033161cb54f194da93e51a11aee6144b
  - >-
    Linux >= 0626e6641f6b467447c81dd7678a69c66f7746cf <
    a4261bbc33fbf99b99c80aa3a2c5097611802980
  - >-
    Linux >= 0626e6641f6b467447c81dd7678a69c66f7746cf <
    f17d1c63a76b0fe8e9c78023a86507a3a6d62cfa
  - >-
    Linux >= 0626e6641f6b467447c81dd7678a69c66f7746cf <
    3aa660c059240e0c795217182cf7df32909dd917
  - Linux 5.15
published: '2025-04-01'
updated: '2026-10-30'
sourceUpdated: '2026-10-30T12:21:02.884Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2025-21955'
references:
  - url: 'https://git.kernel.org/stable/c/8e6508c7ecb1802909f294827eff38f301d0c937'
  - url: 'https://git.kernel.org/stable/c/09aeab68033161cb54f194da93e51a11aee6144b'
  - url: 'https://git.kernel.org/stable/c/a4261bbc33fbf99b99c80aa3a2c5097611802980'
  - url: 'https://git.kernel.org/stable/c/f17d1c63a76b0fe8e9c78023a86507a3a6d62cfa'
  - url: 'https://git.kernel.org/stable/c/3aa660c059240e0c795217182cf7df32909dd917'
tags:
  - cve.org
epss: 0.00502
epssPercentile: 0.43249
ingestedAt: '2026-11-03T15:48:07.702Z'
---

## Overview

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

ksmbd: prevent connection release during oplock break notification

ksmbd_work could be freed when after connection release.
Increment r_count of ksmbd_conn to indicate that requests
are not finished yet and to not release the connection.

## Affected

- `Linux >= 0626e6641f6b467447c81dd7678a69c66f7746cf < 8e6508c7ecb1802909f294827eff38f301d0c937`
- `Linux >= 0626e6641f6b467447c81dd7678a69c66f7746cf < 09aeab68033161cb54f194da93e51a11aee6144b`
- `Linux >= 0626e6641f6b467447c81dd7678a69c66f7746cf < a4261bbc33fbf99b99c80aa3a2c5097611802980`
- `Linux >= 0626e6641f6b467447c81dd7678a69c66f7746cf < f17d1c63a76b0fe8e9c78023a86507a3a6d62cfa`
- `Linux >= 0626e6641f6b467447c81dd7678a69c66f7746cf < 3aa660c059240e0c795217182cf7df32909dd917`
- `Linux 5.15`

## Remediation

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