CVE-2025-21722

Local kernel compromise via stale buffer clearing

Published Feb 27, 2025 · Updated Aug 5, 2026

Use-after-free in the nilfs2 filesystem in Linux allows local users to corrupt kernel memory through a malformed mounted volume. During read-only fallback, nilfs2 page-write callbacks clear busy buffer states without first checking whether another path still references the buffer, allowing the buffer-head ring to be freed while it remains in use. An unprivileged user must reach an already mounted nilfs2 volume and coordinate ordinary filesystem operations with writeback; exploitation can disclose or alter kernel memory, corrupt filesystem data, crash the kernel, or hang filesystem activity.

CVSS severity7.8
High
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in the nilfs2 filesystem in Linux allows local users to corrupt kernel memory through a malformed mounted volume. During read-only fallback, nilfs2 page-write callbacks clear busy buffer states without first checking whether another path still references the buffer, allowing the buffer-head ring to be freed while it remains in use. An unprivileged user must reach an already mounted nilfs2 volume and coordinate ordinary filesystem operations with writeback; exploitation can disclose or alter kernel memory, corrupt filesystem data, crash the kernel, or hang filesystem activity.

The record

CVE
CVE-2025-21722
Published
Feb 27, 2025
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 27, 2025CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=3.10
  2. Affected versionversion=8c26c4e2694a163d525976e804d81cd955bbb40c <1098bb8d52419d262a3358d099a1598a920b730f
  3. Affected versionversion=8c26c4e2694a163d525976e804d81cd955bbb40c <19296737024cd220a1d6590bf4c092bca8c99497
  4. Affected versionversion=8c26c4e2694a163d525976e804d81cd955bbb40c <4d042811c72f71be7c14726db2c72b67025a7cb5
  5. Affected versionversion=8c26c4e2694a163d525976e804d81cd955bbb40c <557ccf5e49f1fb848a29698585bcab2e50a597ef
  6. Affected versionversion=8c26c4e2694a163d525976e804d81cd955bbb40c <7d0544bacc11d6aa26ecd7debf9353193c7a3328
  7. Affected versionversion=8c26c4e2694a163d525976e804d81cd955bbb40c <ca76bb226bf47ff04c782cacbd299f12ddee1ec1
  8. Affected versionversion=8c26c4e2694a163d525976e804d81cd955bbb40c <f51ff43c4c5a6c8e72d0aca89e4d5e688938412f

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=3.10; version=8c26c4e2694a163d525976e804d81cd955bbb40c <1098bb8d52419d262a3358d099a1598a920b730f; version=8c26c4e2694a163d525976e804d81cd955bbb40c <19296737024cd220a1d6590bf4c092bca8c99497; version=8c26c4e2694a163d525976e804d81cd955bbb40c <4d042811c72f71be7c14726db2c72b67025a7cb5; version=8c26c4e2694a163d525976e804d81cd955bbb40c <557ccf5e49f1fb848a29698585bcab2e50a597ef; version=8c26c4e2694a163d525976e804d81cd955bbb40c <7d0544bacc11d6aa26ecd7debf9353193c7a3328; version=8c26c4e2694a163d525976e804d81cd955bbb40c <ca76bb226bf47ff04c782cacbd299f12ddee1ec1; version=8c26c4e2694a163d525976e804d81cd955bbb40c <f51ff43c4c5a6c8e72d0aca89e4d5e688938412f

Published CVSS scores

7.8LinuxCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1068Exploitation for Privilege Escalation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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