---
id: CVE-2025-21666
title: 'vsock: prevent null-ptr-deref in vsock_*[has_data|has_space]'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  vsock: prevent null-ptr-deref in vsock_*[has_data|has_space]

  Recent reports have shown how we sometimes call vsock_*_has_data()
  when a vsock socket has been de-assigne…
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: adp
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= c0cfa2d8a788fcf45df5bf4070ab2474c88d543a <
    daeac89cdb03d30028186f5ff7dc26ec8fa843e7
  - >-
    Linux >= c0cfa2d8a788fcf45df5bf4070ab2474c88d543a <
    9e5fed46ccd2c34c5fa5a9c8825ce4823fdc853e
  - >-
    Linux >= c0cfa2d8a788fcf45df5bf4070ab2474c88d543a <
    b52e50dd4fabd12944172bd486a4f4853b7f74dd
  - >-
    Linux >= c0cfa2d8a788fcf45df5bf4070ab2474c88d543a <
    bc9c49341f9728c31fe248c5fbba32d2e81a092b
  - >-
    Linux >= c0cfa2d8a788fcf45df5bf4070ab2474c88d543a <
    c23d1d4f8efefb72258e9cedce29de10d057f8ca
  - >-
    Linux >= c0cfa2d8a788fcf45df5bf4070ab2474c88d543a <
    91751e248256efc111e52e15115840c35d85abaf
  - Linux 5.5
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2025-10-01T19:52:24.276957Z'
published: '2025-01-31'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T01:02:53.911Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2025-21666'
references:
  - url: 'https://git.kernel.org/stable/c/daeac89cdb03d30028186f5ff7dc26ec8fa843e7'
  - url: 'https://git.kernel.org/stable/c/9e5fed46ccd2c34c5fa5a9c8825ce4823fdc853e'
  - url: 'https://git.kernel.org/stable/c/b52e50dd4fabd12944172bd486a4f4853b7f74dd'
  - url: 'https://git.kernel.org/stable/c/bc9c49341f9728c31fe248c5fbba32d2e81a092b'
  - url: 'https://git.kernel.org/stable/c/c23d1d4f8efefb72258e9cedce29de10d057f8ca'
  - url: 'https://git.kernel.org/stable/c/91751e248256efc111e52e15115840c35d85abaf'
tags:
  - cve.org
epss: 0.00224
epssPercentile: 0.1292
ingestedAt: '2026-10-15T04:46:37.354Z'
---

## Overview

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

vsock: prevent null-ptr-deref in vsock_*[has_data|has_space]

Recent reports have shown how we sometimes call vsock_*_has_data()
when a vsock socket has been de-assigned from a transport (see attached
links), but we shouldn't.

Previous commits should have solved the real problems, but we may have
more in the future, so to avoid null-ptr-deref, we can return 0
(no space, no data available) but with a warning.

This way the code should continue to run in a nearly consistent state
and have a warning that allows us to debug future problems.

## Affected

- `Linux >= c0cfa2d8a788fcf45df5bf4070ab2474c88d543a < daeac89cdb03d30028186f5ff7dc26ec8fa843e7`
- `Linux >= c0cfa2d8a788fcf45df5bf4070ab2474c88d543a < 9e5fed46ccd2c34c5fa5a9c8825ce4823fdc853e`
- `Linux >= c0cfa2d8a788fcf45df5bf4070ab2474c88d543a < b52e50dd4fabd12944172bd486a4f4853b7f74dd`
- `Linux >= c0cfa2d8a788fcf45df5bf4070ab2474c88d543a < bc9c49341f9728c31fe248c5fbba32d2e81a092b`
- `Linux >= c0cfa2d8a788fcf45df5bf4070ab2474c88d543a < c23d1d4f8efefb72258e9cedce29de10d057f8ca`
- `Linux >= c0cfa2d8a788fcf45df5bf4070ab2474c88d543a < 91751e248256efc111e52e15115840c35d85abaf`
- `Linux 5.5`

## Remediation

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