CVE-2025-38256

Local kernel crash via incorrect folio unpinning

Published Jul 9, 2025 · Updated May 11, 2026

Improper folio unpinning in the Linux kernel allows local users to crash the kernel through io_uring buffer teardown. io_release_ubuf passes the folio head to a page-level unpin operation after a tail page was pinned, violating the memory manager's folio accounting. A local low-privileged process must register and release such a buffer; the observed consequence is a kernel BUG and service interruption.

CVSS severity5.5
Medium
EPSS probability0.14%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper folio unpinning in the Linux kernel allows local users to crash the kernel through io_uring buffer teardown. io_release_ubuf passes the folio head to a page-level unpin operation after a tail page was pinned, violating the memory manager's folio accounting. A local low-privileged process must register and release such a buffer; the observed consequence is a kernel BUG and service interruption.

The record

CVE
CVE-2025-38256
Published
Jul 9, 2025
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 9, 2025CVE publishedPublication date reported by the CVE source.
  2. May 11, 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=6.12
  2. Affected versionversion=a8edbb424b1391b077407c75d8f5d2ede77aa70d <11e7b7369e655e6131387b174218d7fa9557b3da
  3. Affected versionversion=a8edbb424b1391b077407c75d8f5d2ede77aa70d <53fd75f25b223878b5fff14932e3a22f42b54f77
  4. Affected versionversion=a8edbb424b1391b077407c75d8f5d2ede77aa70d <5afb4bf9fc62d828647647ec31745083637132e4

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=6.12; version=a8edbb424b1391b077407c75d8f5d2ede77aa70d <11e7b7369e655e6131387b174218d7fa9557b3da; version=a8edbb424b1391b077407c75d8f5d2ede77aa70d <53fd75f25b223878b5fff14932e3a22f42b54f77; version=a8edbb424b1391b077407c75d8f5d2ede77aa70d <5afb4bf9fc62d828647647ec31745083637132e4

Published CVSS scores

5.5UbuntuCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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

T1499Endpoint Denial of Service

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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