CVE-2025-40054Public exploit

Kernel crash via encrypted-page use-after-free

Published Oct 28, 2025 · Updated Oct 28, 2025

Use-after-free in Linux kernel F2FS allows local users to crash or hang the system through concurrent writes to an encrypted file. The f2fs_merge_page_bio() path retains fio->encrypted_page after adding its bounce page to the IPU bio cache, allowing write completion to free the page before f2fs_is_cp_guaranteed() dereferences it. Exploitation requires write access to an fscrypt-encrypted directory on a mounted F2FS volume; successful races panic the kernel or wedge filesystem synchronization.

CVSS severity7.8
High
EPSS probability0.15%
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 Linux kernel F2FS allows local users to crash or hang the system through concurrent writes to an encrypted file. The f2fs_merge_page_bio() path retains fio->encrypted_page after adding its bounce page to the IPU bio cache, allowing write completion to free the page before f2fs_is_cp_guaranteed() dereferences it. Exploitation requires write access to an fscrypt-encrypted directory on a mounted F2FS volume; successful races panic the kernel or wedge filesystem synchronization.

The record

CVE
CVE-2025-40054
Published
Oct 28, 2025
Updated
Oct 28, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
local
Privileges
Unavailable

Timeline

How it unfolded

  1. Oct 28, 2025CVE publishedPublication date reported by the CVE source.
  2. Oct 28, 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=0b20fcec8651569935a10afe03fedc0b812d044e <01118321e0c8a5f3ece57d0d377bfc92d83cd210
  2. Affected versionversion=0b20fcec8651569935a10afe03fedc0b812d044e <edf7e9040fc52c922db947f9c6c36f07377c52ea
  3. Affected versionversion=5.5

What conditions does exploitation require?

Attack vectorlocal
Required privilegesUnavailable in this record.

What is affected?

The Linux Kernel Organization · Linuxversion=0b20fcec8651569935a10afe03fedc0b812d044e <01118321e0c8a5f3ece57d0d377bfc92d83cd210; version=0b20fcec8651569935a10afe03fedc0b812d044e <edf7e9040fc52c922db947f9c6c36f07377c52ea; version=5.5

Published CVSS scores

7.8Linux Kernel CVE TeamCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
5.5Amazon LinuxCVSS: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.

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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
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

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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