CVE-2021-47092

Host warning via stale nested-VMX failure state

Published Mar 4, 2024 · Updated May 11, 2026

Incorrect state handling in Linux KVM 5.15 through 5.15.11 and 5.16-rc1 through 5.16-rc6 allows guest OS users to trigger a host warning. The VMX exit path sets vmx->fail when emulation_required is true in L2 even though invalid guest-state checks require a VM-Exit, leaving nested_vmx_vmexit() with a contradictory state. The user must reach an invalid L2 guest state under nested VMX; the observed consequence is a host WARN during virtual-machine teardown.

CVSS severity5.5
Medium
EPSS probability0.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect state handling in Linux KVM 5.15 through 5.15.11 and 5.16-rc1 through 5.16-rc6 allows guest OS users to trigger a host warning. The VMX exit path sets vmx->fail when emulation_required is true in L2 even though invalid guest-state checks require a VM-Exit, leaving nested_vmx_vmexit() with a contradictory state. The user must reach an invalid L2 guest state under nested VMX; the observed consequence is a host WARN during virtual-machine teardown.

The record

CVE
CVE-2021-47092
Published
Mar 4, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 4, 2024CVE 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=5.15
  2. Affected versionversion=c8607e4a086fae05efe5bffb47c5199c65e7216e <a80dfc025924024d2c61a4c1b8ef62b2fce76a04
  3. Affected versionversion=c8607e4a086fae05efe5bffb47c5199c65e7216e <e4e4e7cb229821cd215031abc47efdab5486a67c

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.15; version=c8607e4a086fae05efe5bffb47c5199c65e7216e <a80dfc025924024d2c61a4c1b8ef62b2fce76a04; version=c8607e4a086fae05efe5bffb47c5199c65e7216e <e4e4e7cb229821cd215031abc47efdab5486a67c

Published CVSS scores

5.5NIST NVDCVSS: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.

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
Privilegesauthenticated
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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