CVE-2025-40102

Host crash via pre-init vCPU event ioctl

Published Oct 30, 2025 · Updated Oct 30, 2025

Denial of service in arm64 KVM in Linux 4.19 through 6.17.4 allows local users with KVM access to crash the host via a vCPU ioctl. KVM_SET_VCPU_EVENTS accepts pending events before KVM_ARM_VCPU_INIT, so exception routing consumes uninitialized vCPU state and can set an illegal AArch64 mode. Access to the KVM vCPU ioctl interface is required; triggering the bad state reaches exception_target_el() and crashes the host kernel.

CVSS severity5.5
Medium
EPSS probability0.21%
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 arm64 KVM in Linux 4.19 through 6.17.4 allows local users with KVM access to crash the host via a vCPU ioctl. KVM_SET_VCPU_EVENTS accepts pending events before KVM_ARM_VCPU_INIT, so exception routing consumes uninitialized vCPU state and can set an illegal AArch64 mode. Access to the KVM vCPU ioctl interface is required; triggering the bad state reaches exception_target_el() and crashes the host kernel.

The record

CVE
CVE-2025-40102
Published
Oct 30, 2025
Updated
Oct 30, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 30, 2025CVE publishedPublication date reported by the CVE source.
  2. Oct 30, 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=4.19
  2. Affected versionversion=b7b27facc7b50a5fce0afaa3df56157136ce181a <0aa1b76fe1429629215a7c79820e4b96233ac4a3
  3. Affected versionversion=b7b27facc7b50a5fce0afaa3df56157136ce181a <64a04e6320fc5affbadc59dc7024d79f909bfe84

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4.19; version=b7b27facc7b50a5fce0afaa3df56157136ce181a <0aa1b76fe1429629215a7c79820e4b96233ac4a3; version=b7b27facc7b50a5fce0afaa3df56157136ce181a <64a04e6320fc5affbadc59dc7024d79f909bfe84

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Application or System Exploitation

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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