CVE-2021-46978

Nested guest compromise via unmapped eVMCS synchronization

Published Feb 28, 2024 · Updated May 23, 2026

State synchronization flaw in Linux KVM 5.10.13 through 5.10.37 and 5.11 allows local users to corrupt nested guest state. During nested-state restoration with enlightened VMCS, nested_vmx_vmexit() clears KVM_REQ_GET_NESTED_STATE_PAGES before nested_sync_vmcs12_to_shadow() maps eVMCS, so VMCS12 changes are not copied into the enlightened VMCS. Exploitation requires low-privileged local access to an x86 KVM host using nested VMX and a migration or restore path, and the resulting stale control state can compromise a nested guest.

CVSS severity7.8
High
EPSS probability0.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

State synchronization flaw in Linux KVM 5.10.13 through 5.10.37 and 5.11 allows local users to corrupt nested guest state. During nested-state restoration with enlightened VMCS, nested_vmx_vmexit() clears KVM_REQ_GET_NESTED_STATE_PAGES before nested_sync_vmcs12_to_shadow() maps eVMCS, so VMCS12 changes are not copied into the enlightened VMCS. Exploitation requires low-privileged local access to an x86 KVM host using nested VMX and a migration or restore path, and the resulting stale control state can compromise a nested guest.

The record

CVE
CVE-2021-46978
Published
Feb 28, 2024
Updated
May 23, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
Unavailable
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 28, 2024CVE publishedPublication date reported by the CVE source.
  2. May 23, 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=0faceb7d6dda6f370ff1fa0464d7180f7e5cb417 <c8bf64e3fb77cc19bad146fbe26651985b117194
  2. Affected versionversion=5.10.13 <5.10.38
  3. Affected versionversion=5.11
  4. Affected versionversion=f2c7ef3ba9556d62a7e2bb23b563c6510007d55c <200a45649ab7361bc80c70aebf7165b64f9a6c9f
  5. Affected versionversion=f2c7ef3ba9556d62a7e2bb23b563c6510007d55c <bd0e8455b85b651a4c77de9616e307129b15aaa7
  6. Affected versionversion=f2c7ef3ba9556d62a7e2bb23b563c6510007d55c <f5c7e8425f18fdb9bdb7d13340651d7876890329

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=0faceb7d6dda6f370ff1fa0464d7180f7e5cb417 <c8bf64e3fb77cc19bad146fbe26651985b117194; version=5.10.13 <5.10.38; version=5.11; version=f2c7ef3ba9556d62a7e2bb23b563c6510007d55c <200a45649ab7361bc80c70aebf7165b64f9a6c9f; version=f2c7ef3ba9556d62a7e2bb23b563c6510007d55c <bd0e8455b85b651a4c77de9616e307129b15aaa7; version=f2c7ef3ba9556d62a7e2bb23b563c6510007d55c <f5c7e8425f18fdb9bdb7d13340651d7876890329
The Linux Kernel Organization · Linux Kernelversion=0 <5.11*; version=0faceb7d6dda <c8bf64e3fb77; version=5.10.38 <=5.11*; version=5.11; version=5.12.5 <=5.12*; version=5.13 <=*; version=f2c7ef3ba955 <200a45649ab7; version=f2c7ef3ba955 <bd0e8455b85b; version=f2c7ef3ba955 <f5c7e8425f18

Published CVSS scores

7.8CanonicalCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
7.8CISA-ADPCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

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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

No sourced classifications are available.

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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