CVE-2025-40119

Kernel crash via unchecked ext4 cleanup pointer

Published Nov 12, 2025 · Updated May 11, 2026

Null pointer dereference in Linux kernel 6.17 through 6.17.2 allows attackers to crash the kernel during an ext4 mount. ext4_mb_init calls cleanup while s_mb_avg_fragment_size can remain uninitialized, and the destroy function dereferences it without a null check. Reachability requires an ext4 mount while groupinfo slab-cache allocation fails; the documented result is a kernel Oops and service interruption.

CVSS severityUnavailable
Unscored
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

Null pointer dereference in Linux kernel 6.17 through 6.17.2 allows attackers to crash the kernel during an ext4 mount. ext4_mb_init calls cleanup while s_mb_avg_fragment_size can remain uninitialized, and the destroy function dereferences it without a null check. Reachability requires an ext4 mount while groupinfo slab-cache allocation fails; the documented result is a kernel Oops and service interruption.

The record

CVE
CVE-2025-40119
Published
Nov 12, 2025
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
local
Privileges
Unavailable

Timeline

How it unfolded

  1. Nov 12, 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=6.17
  2. Affected versionversion=d99d714f714c9492dc64d8ab4329b083dbfa9cab <08d9175578d6a8e9b81921898fbf01aa669cd2be
  3. Affected versionversion=f7eaacbb4e54f8a6c6674c16eff54f703ea63d5e <00110f3cfc9b34b2dfee2a6c9e55a0ae6df125ae
  4. Affected versionversion=f7eaacbb4e54f8a6c6674c16eff54f703ea63d5e <3c3fac6bc0a9c00dbe65d8dc0d3a282afe4d3188

What conditions does exploitation require?

Attack vectorlocal
Required privilegesUnavailable in this record.

What is affected?

The Linux Kernel Organization · Linuxversion=6.17; version=d99d714f714c9492dc64d8ab4329b083dbfa9cab <08d9175578d6a8e9b81921898fbf01aa669cd2be; version=f7eaacbb4e54f8a6c6674c16eff54f703ea63d5e <00110f3cfc9b34b2dfee2a6c9e55a0ae6df125ae; version=f7eaacbb4e54f8a6c6674c16eff54f703ea63d5e <3c3fac6bc0a9c00dbe65d8dc0d3a282afe4d3188

Published CVSS scores

No CVSS assessment is available in this record.

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 exploitUnconfirmed

Weakness, pattern, technique

T1499.004Application or System Exploitation

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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