CVE-2021-47062

Host crash via premature vCPU iteration

Published Feb 29, 2024 · Updated May 11, 2026

Null-pointer dereference in Linux kernel KVM SVM 5.11 before 5.11.21 and 5.12 before 5.12.4 allows local users to crash the host. The SEV VMSA encryption path iterates created_vcpus, whose count increments before each vCPU pointer is installed, and dereferences a missing entry during concurrent KVM_CREATE_VCPU operations. Triggering the flaw requires local KVM access, AMD SVM with SEV, and a creation race; the bounded consequence is a host-kernel crash.

CVSS severity5.5
Medium
EPSS probability0.22%
Next 30 days · Sep 17, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Null-pointer dereference in Linux kernel KVM SVM 5.11 before 5.11.21 and 5.12 before 5.12.4 allows local users to crash the host. The SEV VMSA encryption path iterates created_vcpus, whose count increments before each vCPU pointer is installed, and dereferences a missing entry during concurrent KVM_CREATE_VCPU operations. Triggering the flaw requires local KVM access, AMD SVM with SEV, and a creation race; the bounded consequence is a host-kernel crash.

The record

CVE
CVE-2021-47062
Published
Feb 29, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-476, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 29, 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=ad73109ae7ec30d5bfb76be108e304f9f0af4829 <ba7bf5d6336aa9c0d977b161bfa420c56d46ee40
  3. Affected versionversion=ad73109ae7ec30d5bfb76be108e304f9f0af4829 <bd0cced2ae93195668f983d443f7f17e8efd24d2
  4. Affected versionversion=ad73109ae7ec30d5bfb76be108e304f9f0af4829 <c36b16d29f3af5f32fc1b2a3401bf48f71cabee1

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.11; version=ad73109ae7ec30d5bfb76be108e304f9f0af4829 <ba7bf5d6336aa9c0d977b161bfa420c56d46ee40; version=ad73109ae7ec30d5bfb76be108e304f9f0af4829 <bd0cced2ae93195668f983d443f7f17e8efd24d2; version=ad73109ae7ec30d5bfb76be108e304f9f0af4829 <c36b16d29f3af5f32fc1b2a3401bf48f71cabee1

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.

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No observations available

Sep 11, 2026Sep 17, 2026
Latest reporting daySep 17, 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
T1499.004Application or System Exploitation

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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