CVE-2025-40218

CPU hang via repeated page-table walk retry

Published Dec 4, 2025 · Updated May 11, 2026

A soft-lockup flaw in Linux 6.5 and affected later branches allows local users to hang a CPU via concurrent DAMON and CPU hotplug operations. In mm/damon/vaddr.c, the page-table walk callback returns ACTION_AGAIN whenever pte_offset_map_lock() fails, even when a PMD migration entry makes repeated failure persistent. The demonstrated condition requires privileged DAMON virtual-address monitoring to overlap CPU hotplug; the endless retry prevents the walk from completing.

CVSS severityUnavailable
Unscored
EPSS probability0.19%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A soft-lockup flaw in Linux 6.5 and affected later branches allows local users to hang a CPU via concurrent DAMON and CPU hotplug operations. In mm/damon/vaddr.c, the page-table walk callback returns ACTION_AGAIN whenever pte_offset_map_lock() fails, even when a PMD migration entry makes repeated failure persistent. The demonstrated condition requires privileged DAMON virtual-address monitoring to overlap CPU hotplug; the endless retry prevents the walk from completing.

The record

CVE
CVE-2025-40218
Published
Dec 4, 2025
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
local
Privileges
Unavailable

Timeline

How it unfolded

  1. Dec 4, 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=6.5
  2. Affected versionversion=7780d04046a2288ab85d88bedacc60fa4fad9971 <0ccd91cf749536d41307a07e60ec14ab0dbf21f5
  3. Affected versionversion=7780d04046a2288ab85d88bedacc60fa4fad9971 <677ebfe5d00f94adec0c0204f6e6e2a82d3f77bf
  4. Affected versionversion=7780d04046a2288ab85d88bedacc60fa4fad9971 <ac42320ec873bfe726141069cfdd90ee5bc4e885
  5. Affected versionversion=7780d04046a2288ab85d88bedacc60fa4fad9971 <b93af2cc8e036754c0d9970d9ddc47f43cc94b9f

What conditions does exploitation require?

Attack vectorlocal
Required privilegesUnavailable in this record.

What is affected?

The Linux Kernel Organization · Linuxversion=6.5; version=7780d04046a2288ab85d88bedacc60fa4fad9971 <0ccd91cf749536d41307a07e60ec14ab0dbf21f5; version=7780d04046a2288ab85d88bedacc60fa4fad9971 <677ebfe5d00f94adec0c0204f6e6e2a82d3f77bf; version=7780d04046a2288ab85d88bedacc60fa4fad9971 <ac42320ec873bfe726141069cfdd90ee5bc4e885; version=7780d04046a2288ab85d88bedacc60fa4fad9971 <b93af2cc8e036754c0d9970d9ddc47f43cc94b9f

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.

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
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499Endpoint Denial of Service

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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