CVE-2025-39691

Kernel memory corruption via buffer-head use-after-free

Published Sep 5, 2025 · Updated Sep 5, 2025

Use-after-free in affected Linux kernel branches allows local users to corrupt kernel memory through reads from a mounted NTFS3 volume. In mpage_read_folio(), map_bh remains on the caller's stack while end_buffer_read_sync() unlocks it before dropping its reference, allowing the waiter to reclaim the stack before put_bh() runs. Read access to a file on an already mounted NTFS3 filesystem is sufficient; the resulting corruption compromises kernel-memory confidentiality and integrity or crashes the kernel.

CVSS severity7.8
High
EPSS probability0.17%
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 affected Linux kernel branches allows local users to corrupt kernel memory through reads from a mounted NTFS3 volume. In mpage_read_folio(), map_bh remains on the caller's stack while end_buffer_read_sync() unlocks it before dropping its reference, allowing the waiter to reclaim the stack before put_bh() runs. Read access to a file on an already mounted NTFS3 filesystem is sufficient; the resulting corruption compromises kernel-memory confidentiality and integrity or crashes the kernel.

The record

CVE
CVE-2025-39691
Published
Sep 5, 2025
Updated
Sep 5, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
Unavailable
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 5, 2025CVE publishedPublication date reported by the CVE source.
  2. Sep 5, 2025Record 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=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <03b40bf5d0389ca23ae6857ee25789f0e0b47ce8
  2. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <042cf48ecf67f72c8b3846c7fac678f472712ff3
  3. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <3169edb8945c295cf89120fc6b2c35cfe3ad4c9e
  4. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <70a09115da586bf662c3bae9c0c4a1b99251fad9
  5. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <7375f22495e7cd1c5b3b5af9dcc4f6dffe34ce49
  6. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <90b5193edb323fefbee0e4e5bc39ed89dcc37719
  7. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <c58c6b532b7b69537cfd9ef701c7e37cdcf79dc4
  8. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <c5aa6ba1127307ab5dc3773eaf40d73a3423841f
  9. Affected versionversion=2.6.12

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <03b40bf5d0389ca23ae6857ee25789f0e0b47ce8; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <042cf48ecf67f72c8b3846c7fac678f472712ff3; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <3169edb8945c295cf89120fc6b2c35cfe3ad4c9e; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <70a09115da586bf662c3bae9c0c4a1b99251fad9; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <7375f22495e7cd1c5b3b5af9dcc4f6dffe34ce49; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <90b5193edb323fefbee0e4e5bc39ed89dcc37719; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <c58c6b532b7b69537cfd9ef701c7e37cdcf79dc4; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <c5aa6ba1127307ab5dc3773eaf40d73a3423841f; version=2.6.12

Published CVSS scores

7.8Linux kernel CNACVSS: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

No sourced classifications are available.

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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