CVE-2021-47450

Host page-table corruption via tail-page misrefcounting

Published May 22, 2024 · Updated Aug 5, 2026

Page-table corruption in arm64 KVM 5.13 through 5.14.14 and 5.15-rc1 through 5.15-rc6 allows local users to corrupt host mappings. host_s2_zalloc_pages_exact leaves a concatenated PGD as one compound page while KVM refcounts its constituent pages individually, allowing live tail-page counts to reach zero. Reachability requires an arm64 host running KVM in protected mode; exploitation can compromise host memory mappings or interrupt the host.

CVSS severity8.8
High
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Page-table corruption in arm64 KVM 5.13 through 5.14.14 and 5.15-rc1 through 5.15-rc6 allows local users to corrupt host mappings. host_s2_zalloc_pages_exact leaves a concatenated PGD as one compound page while KVM refcounts its constituent pages individually, allowing live tail-page counts to reach zero. Reachability requires an arm64 host running KVM in protected mode; exploitation can compromise host memory mappings or interrupt the host.

The record

CVE
CVE-2021-47450
Published
May 22, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 22, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 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=1025c8c0c6accfcbdc8f52ca1940160f65cd87d6 <1d58a17ef54599506d44c45ac95be27273a4d2b1
  2. Affected versionversion=1025c8c0c6accfcbdc8f52ca1940160f65cd87d6 <b372264c66ef78f2cab44e877fbd765ad6d24c39
  3. Affected versionversion=5.13

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=1025c8c0c6accfcbdc8f52ca1940160f65cd87d6 <1d58a17ef54599506d44c45ac95be27273a4d2b1; version=1025c8c0c6accfcbdc8f52ca1940160f65cd87d6 <b372264c66ef78f2cab44e877fbd765ad6d24c39; version=5.13

Published CVSS scores

8.8kernel.orgCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
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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