CVE-2026-45987

L2 vCPU hang via stale interrupt shadow

Published May 27, 2026 · Updated May 27, 2026

Denial of service in Linux Kernel KVM nSVM allows local users to hang an L2 vCPU during nested-state restoration. nested_sync_control_from_vmcb02() fails to copy the CPU-written SVM_INTERRUPT_SHADOW_MASK from vmcb02 into cached vmcb12 after L2 VMRUN. When KVM_SET_VCPU_EVENTS precedes KVM_SET_NESTED_STATE, the shadow is restored to vmcb01, and a wakeup interrupt before a shadowed HLT can hang L2.

CVSS severity5.5
Medium
EPSS probability0.12%
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 Kernel KVM nSVM allows local users to hang an L2 vCPU during nested-state restoration. nested_sync_control_from_vmcb02() fails to copy the CPU-written SVM_INTERRUPT_SHADOW_MASK from vmcb02 into cached vmcb12 after L2 VMRUN. When KVM_SET_VCPU_EVENTS precedes KVM_SET_NESTED_STATE, the shadow is restored to vmcb01, and a wakeup interrupt before a shadowed HLT can hang L2.

The record

CVE
CVE-2026-45987
Published
May 27, 2026
Updated
May 27, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 27, 2026CVE publishedPublication date reported by the CVE source.
  2. May 27, 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=5.8
  2. Affected versionversion=cc440cdad5b7a4c1de12dace725209eb3e0cf663 <03bee264f8ebfd39e0254c98e112d033a7aa9055
  3. Affected versionversion=cc440cdad5b7a4c1de12dace725209eb3e0cf663 <1709418535a8df95532999d61b03d59975280258
  4. Affected versionversion=cc440cdad5b7a4c1de12dace725209eb3e0cf663 <2f950eeb27af6885416232761700b8820cae0a61
  5. Affected versionversion=cc440cdad5b7a4c1de12dace725209eb3e0cf663 <497f6af9679fc9c6ce2f438e11ed5d51b1aa8297
  6. Affected versionversion=cc440cdad5b7a4c1de12dace725209eb3e0cf663 <e0377e52f3c10ee572732d11b04625b7f517a862

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=5.8; version=cc440cdad5b7a4c1de12dace725209eb3e0cf663 <03bee264f8ebfd39e0254c98e112d033a7aa9055; version=cc440cdad5b7a4c1de12dace725209eb3e0cf663 <1709418535a8df95532999d61b03d59975280258; version=cc440cdad5b7a4c1de12dace725209eb3e0cf663 <2f950eeb27af6885416232761700b8820cae0a61; version=cc440cdad5b7a4c1de12dace725209eb3e0cf663 <497f6af9679fc9c6ce2f438e11ed5d51b1aa8297; version=cc440cdad5b7a4c1de12dace725209eb3e0cf663 <e0377e52f3c10ee572732d11b04625b7f517a862

Published CVSS scores

5.5NVDCVSS: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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Endpoint Denial of Service: Application 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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