CVE-2025-40195

Local denial of service via NULL namespace dereference

Published Nov 12, 2025 · Updated May 11, 2026

NULL-pointer dereference in the listmount path of the Linux kernel allows local users to interrupt service through a crafted syscall. In fs/namespace.c, mnt_ns_release() unconditionally dereferences the namespace pointer to decrement its passive reference count even when listmount() supplies NULL. Reaching listmount() requires CAP_SYS_ADMIN in the caller's user namespace, and exploitation affects availability without documented data disclosure or modification.

CVSS severity5.5
Medium
EPSS probability0.18%
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 the listmount path of the Linux kernel allows local users to interrupt service through a crafted syscall. In fs/namespace.c, mnt_ns_release() unconditionally dereferences the namespace pointer to decrement its passive reference count even when listmount() supplies NULL. Reaching listmount() requires CAP_SYS_ADMIN in the caller's user namespace, and exploitation affects availability without documented data disclosure or modification.

The record

CVE
CVE-2025-40195
Published
Nov 12, 2025
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
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=1901c92497bd90caf608a474f1bf4d8795b372a2 <2d68f8a7379d9c61005e982600c61948d4d019bd
  2. Affected versionversion=1901c92497bd90caf608a474f1bf4d8795b372a2 <6c7ca6a02f8f9549a438a08a23c6327580ecf3d6
  3. Affected versionversion=1901c92497bd90caf608a474f1bf4d8795b372a2 <99ae3e70a293834d0274c46a37120c71a24a4995
  4. Affected versionversion=6.11

What conditions does exploitation require?

Attack vectorlocal
Required privilegesUnavailable in this record.

What is affected?

The Linux Kernel Organization · Linuxversion=1901c92497bd90caf608a474f1bf4d8795b372a2 <2d68f8a7379d9c61005e982600c61948d4d019bd; version=1901c92497bd90caf608a474f1bf4d8795b372a2 <6c7ca6a02f8f9549a438a08a23c6327580ecf3d6; version=1901c92497bd90caf608a474f1bf4d8795b372a2 <99ae3e70a293834d0274c46a37120c71a24a4995; version=6.11

Published CVSS scores

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 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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