CVE-2025-40237

Local crash via unlocked overlayfs handle encoding

Published Dec 4, 2025 · Updated May 23, 2026

A race in Linux kernel fs/notify allows local users to crash the system by reading inotify fdinfo during an overlayfs unmount. The show_mark_fhandle path calls exportfs_encode_fid without holding s_umount, so ovl_check_encode_origin dereferences i_sb->s_root after unmount clears it. Triggering the fault requires an inotify descriptor watching an overlayfs inode while that filesystem is unmounted, and the resulting kernel oops interrupts service.

CVSS severity5.8
Medium
EPSS probability0.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A race in Linux kernel fs/notify allows local users to crash the system by reading inotify fdinfo during an overlayfs unmount. The show_mark_fhandle path calls exportfs_encode_fid without holding s_umount, so ovl_check_encode_origin dereferences i_sb->s_root after unmount clears it. Triggering the fault requires an inotify descriptor watching an overlayfs inode while that filesystem is unmounted, and the resulting kernel oops interrupts service.

The record

CVE
CVE-2025-40237
Published
Dec 4, 2025
Updated
May 23, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Dec 4, 2025CVE publishedPublication date reported by the CVE source.
  2. May 23, 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=3c7c90274ae339e1ad443c9be1c67a20b80b9c76 <3f307a9f7a7a2822e38ac451b73e2244e7279496
  2. Affected versionversion=6.12.10 <6.12.56
  3. Affected versionversion=6.13
  4. Affected versionversion=6.6.72 <6.6.73
  5. Affected versionversion=6.6.74 <6.6.115
  6. Affected versionversion=a1a541fbfa7e97c1100144db34b57553d7164ce5 <950b604384fd75d62e860bec7135b2b62eb4d508
  7. Affected versionversion=c45beebfde34aa71afbc48b2c54cdda623515037 <a7c4bb43bfdc2b9f06ee9d036028ed13a83df42a
  8. Affected versionversion=c45beebfde34aa71afbc48b2c54cdda623515037 <d1894bc542becb0fda61e7e513b09523cab44030
  9. Affected versionversion=f0c0ac84de17c37e6e84da65fb920f91dada55ad <bc1c6b803e14ea2b8f7e33b7164013f666ceb656

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=3c7c90274ae339e1ad443c9be1c67a20b80b9c76 <3f307a9f7a7a2822e38ac451b73e2244e7279496; version=6.12.10 <6.12.56; version=6.13; version=6.6.72 <6.6.73; version=6.6.74 <6.6.115; version=a1a541fbfa7e97c1100144db34b57553d7164ce5 <950b604384fd75d62e860bec7135b2b62eb4d508; version=c45beebfde34aa71afbc48b2c54cdda623515037 <a7c4bb43bfdc2b9f06ee9d036028ed13a83df42a; version=c45beebfde34aa71afbc48b2c54cdda623515037 <d1894bc542becb0fda61e7e513b09523cab44030; version=f0c0ac84de17c37e6e84da65fb920f91dada55ad <bc1c6b803e14ea2b8f7e33b7164013f666ceb656

Published CVSS scores

5.8OracleCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 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.

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Technologies

Your stack

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Your stack

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