CVE-2025-38506

Host CPU lockup via unyielding memory loop

Published Aug 16, 2025 · Updated May 11, 2026

Denial of service in Linux KVM allows local users to trigger a host CPU soft lockup through a whole-guest memory-attribute update. The kvm_vm_set_mem_attributes() loops reserve and store per-page attributes without yielding the CPU, so very large ranges keep the host in kernel mode. Reaching the condition requires an SEV-SNP guest with at least 1 TB of memory and access to issue its KVM memory-attribute ioctl; the resulting interruption is confined to host CPU availability.

CVSS severity5.5
Medium
EPSS probability0.11%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Linux KVM allows local users to trigger a host CPU soft lockup through a whole-guest memory-attribute update. The kvm_vm_set_mem_attributes() loops reserve and store per-page attributes without yielding the CPU, so very large ranges keep the host in kernel mode. Reaching the condition requires an SEV-SNP guest with at least 1 TB of memory and access to issue its KVM memory-attribute ioctl; the resulting interruption is confined to host CPU availability.

The record

CVE
CVE-2025-38506
Published
Aug 16, 2025
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 16, 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=5a475554db1e476a14216e742ea2bdb77362d5d5 <1ef45ae7a3938f0844032ba670b4f89180a5bffc
  2. Affected versionversion=5a475554db1e476a14216e742ea2bdb77362d5d5 <47bb584237cc285e3a860b70c01f7bda9dcfb05b
  3. Affected versionversion=5a475554db1e476a14216e742ea2bdb77362d5d5 <d9bd1163c8d8f716f45e54d034ee28757cc85549
  4. Affected versionversion=6.8

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5a475554db1e476a14216e742ea2bdb77362d5d5 <1ef45ae7a3938f0844032ba670b4f89180a5bffc; version=5a475554db1e476a14216e742ea2bdb77362d5d5 <47bb584237cc285e3a860b70c01f7bda9dcfb05b; version=5a475554db1e476a14216e742ea2bdb77362d5d5 <d9bd1163c8d8f716f45e54d034ee28757cc85549; version=6.8

Published CVSS scores

5.5UbuntuCVSS: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
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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