CVE-2025-40038

Host denial of service via invalid fastpath sleep

Published Oct 28, 2025 · Updated Oct 28, 2025

Denial of service in Linux KVM SVM allows guest OS users to hang or panic an affected host through an HLT or WRMSR VM exit. When next RIP is invalid, svm_exit_handlers_fastpath invokes instruction decoding that reads guest memory and can sleep while hard IRQs remain disabled. The path requires an AMD SVM host without NRIPS, nrips=0, or a zero next_rip; consequences include repeated warnings, VM termination, host panic, or hard lockup.

CVSS severity7.1
High
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

Denial of service in Linux KVM SVM allows guest OS users to hang or panic an affected host through an HLT or WRMSR VM exit. When next RIP is invalid, svm_exit_handlers_fastpath invokes instruction decoding that reads guest memory and can sleep while hard IRQs remain disabled. The path requires an AMD SVM host without NRIPS, nrips=0, or a zero next_rip; consequences include repeated warnings, VM termination, host panic, or hard lockup.

The record

CVE
CVE-2025-40038
Published
Oct 28, 2025
Updated
Oct 28, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
local
Privileges
unauthenticated

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=6.5
  2. Affected versionversion=b439eb8ab578557263815ba8581d02c1b730e348 <0910dd7c9ad45a2605c45fd2bf3d1bcac087687c
  3. Affected versionversion=b439eb8ab578557263815ba8581d02c1b730e348 <cd3efb93677c4b0cf76348882fb429165fee33fd
  4. Affected versionversion=b439eb8ab578557263815ba8581d02c1b730e348 <da2a3c231f7f2a5ac146d972b8c1d7d84aff6d70
  5. Affected versionversion=b439eb8ab578557263815ba8581d02c1b730e348 <f994e9c790ce97d3cf01af4d0a1b9add0c955aee

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=6.5; version=b439eb8ab578557263815ba8581d02c1b730e348 <0910dd7c9ad45a2605c45fd2bf3d1bcac087687c; version=b439eb8ab578557263815ba8581d02c1b730e348 <cd3efb93677c4b0cf76348882fb429165fee33fd; version=b439eb8ab578557263815ba8581d02c1b730e348 <da2a3c231f7f2a5ac146d972b8c1d7d84aff6d70; version=b439eb8ab578557263815ba8581d02c1b730e348 <f994e9c790ce97d3cf01af4d0a1b9add0c955aee

Published CVSS scores

7.1UbuntuCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/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
Privilegesunauthenticated
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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