CVE-2025-40072Public exploit

Local service interruption via unchecked mount namespace

Published Oct 28, 2025 · Updated Oct 28, 2025

NULL-pointer dereference in Linux kernel 6.16 through 6.17.2 allows local users to interrupt service through a fanotify mark. do_fanotify_mark() dereferences mntns->user_ns without checking whether mnt_ns_from_dentry() returned NULL for a path that is not a mount namespace object. A low-privileged local user can trigger the kernel Oops inside user and mount namespaces, terminating the process and disrupting the host.

CVSS severity5.5
Medium
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

NULL-pointer dereference in Linux kernel 6.16 through 6.17.2 allows local users to interrupt service through a fanotify mark. do_fanotify_mark() dereferences mntns->user_ns without checking whether mnt_ns_from_dentry() returned NULL for a path that is not a mount namespace object. A low-privileged local user can trigger the kernel Oops inside user and mount namespaces, terminating the process and disrupting the host.

The record

CVE
CVE-2025-40072
Published
Oct 28, 2025
Updated
Oct 28, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
local
Privileges
authenticated

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=58f5fbeb367ff6f30a2448b2cad70f70b2de4b06 <62e59ffe8787b5550ccff70c30b6f6be6a3ac3dd
  2. Affected versionversion=58f5fbeb367ff6f30a2448b2cad70f70b2de4b06 <73ce2a774ad6497cbd48dc4f8a5d699bc417f3fa
  3. Affected versionversion=6.16

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=58f5fbeb367ff6f30a2448b2cad70f70b2de4b06 <62e59ffe8787b5550ccff70c30b6f6be6a3ac3dd; version=58f5fbeb367ff6f30a2448b2cad70f70b2de4b06 <73ce2a774ad6497cbd48dc4f8a5d699bc417f3fa; version=6.16

Published CVSS scores

5.5SUSECVSS: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 exploitPublished

Weakness, pattern, technique

T1499.004Application 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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