CVE-2021-47230

Host crash via stale KVM SMM state

Published May 21, 2024 · Updated May 11, 2026

NULL pointer dereference in x86 KVM in affected Linux kernel builds allows local users to crash the host through a failed guest RSM. When RSM fails, KVM exits without post_leave_smm(), leaving the MMU role's SMM flag set while vCPU SMM is clear; gfn_to_rmap then uses mismatched memslot sets and dereferences a null rmap. Reaching the fault requires local low-privileged access, user interaction, an x86 KVM guest, a failed RSM path, and a subsequent page fault; the bounded result is a host crash.

CVSS severity6.6
Medium
EPSS probability0.23%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in x86 KVM in affected Linux kernel builds allows local users to crash the host through a failed guest RSM. When RSM fails, KVM exits without post_leave_smm(), leaving the MMU role's SMM flag set while vCPU SMM is clear; gfn_to_rmap then uses mismatched memslot sets and dereferences a null rmap. Reaching the fault requires local low-privileged access, user interaction, an x86 KVM guest, a failed RSM path, and a subsequent page fault; the bounded result is a host crash.

The record

CVE
CVE-2021-47230
Published
May 21, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-476, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 21, 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=5.1
  2. Affected versionversion=9ec19493fb86d6d5fbf9286b94ff21e56ef66376 <669a8866e468fd020d34eb00e08cb41d3774b71b
  3. Affected versionversion=9ec19493fb86d6d5fbf9286b94ff21e56ef66376 <78fcb2c91adfec8ce3a2ba6b4d0dda89f2f4a7c6
  4. Affected versionversion=9ec19493fb86d6d5fbf9286b94ff21e56ef66376 <cbb425f62df9df7abee4b3f068f7ed6ffc3561e2
  5. Affected versionversion=9ec19493fb86d6d5fbf9286b94ff21e56ef66376 <df9a40cfb3be2cbeb1c17bb67c59251ba16630f3

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.1; version=9ec19493fb86d6d5fbf9286b94ff21e56ef66376 <669a8866e468fd020d34eb00e08cb41d3774b71b; version=9ec19493fb86d6d5fbf9286b94ff21e56ef66376 <78fcb2c91adfec8ce3a2ba6b4d0dda89f2f4a7c6; version=9ec19493fb86d6d5fbf9286b94ff21e56ef66376 <cbb425f62df9df7abee4b3f068f7ed6ffc3561e2; version=9ec19493fb86d6d5fbf9286b94ff21e56ef66376 <df9a40cfb3be2cbeb1c17bb67c59251ba16630f3
The Linux Kernel Organization · Linux Kernelversion=5.1; version=9ec19493fb86 <669a8866e468; version=9ec19493fb86 <78fcb2c91adf; version=9ec19493fb86 <cbb425f62df9; version=9ec19493fb86 <df9a40cfb3be

Published CVSS scores

6.6CISA ADP VulnrichmentCVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:N/I:H/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

CWE-476NULL Pointer Dereference
T1499Endpoint Denial of Service

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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