CVE-2021-47008

Host kernel crash via unmapped GHCB update

Published Feb 28, 2024 · Updated May 11, 2026

NULL pointer dereference in Linux KVM SVM 5.11 allows guest OS users to crash the host kernel through crafted SIPI handling. sev_vcpu_deliver_sipi_vector and svm_complete_emulated_msr update the GHCB without first ensuring that the prior VM exit mapped it. Reachability requires an AMD SEV guest and either a SIPI without AP Reset Hold or an emulated MSR error path; the documented consequence is host availability loss.

CVSS severity5.5
Medium
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

NULL pointer dereference in Linux KVM SVM 5.11 allows guest OS users to crash the host kernel through crafted SIPI handling. sev_vcpu_deliver_sipi_vector and svm_complete_emulated_msr update the GHCB without first ensuring that the prior VM exit mapped it. Reachability requires an AMD SEV guest and either a SIPI without AP Reset Hold or an emulated MSR error path; the documented consequence is host availability loss.

The record

CVE
CVE-2021-47008
Published
Feb 28, 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. Feb 28, 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=5.11
  2. Affected versionversion=f1c6366e304328de301be362eca905a3503ff33b <a3ba26ecfb569f4aa3f867e80c02aa65f20aadad
  3. Affected versionversion=f1c6366e304328de301be362eca905a3503ff33b <fb9e14f4f8217a0980f8da2c8ff70dee058cbe47
  4. Affected versionversion=f1c6366e304328de301be362eca905a3503ff33b <fd722a57fe0b80133dacae4e1c852ee4212f9b2e

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.11; version=f1c6366e304328de301be362eca905a3503ff33b <a3ba26ecfb569f4aa3f867e80c02aa65f20aadad; version=f1c6366e304328de301be362eca905a3503ff33b <fb9e14f4f8217a0980f8da2c8ff70dee058cbe47; version=f1c6366e304328de301be362eca905a3503ff33b <fd722a57fe0b80133dacae4e1c852ee4212f9b2e

Published CVSS scores

5.5UbuntuCVSS: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

CWE-476NULL Pointer Dereference
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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