CVE-2021-47632

Local denial of service via recursive page-table lock

Published Feb 26, 2025 · Updated May 11, 2026

Improper locking in the Linux kernel 5.14 and affected later branches allows local users to hang PowerPC systems during page-attribute changes. change_page_attr() takes the page-table spinlock around a read-modify-write operation even though pte_update() already makes that update atomic, causing recursive lock acquisition. The flaw requires local low-privileged access on a PowerPC kernel and can deny service without disclosing or modifying data.

CVSS severity5.5
Medium
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper locking in the Linux kernel 5.14 and affected later branches allows local users to hang PowerPC systems during page-attribute changes. change_page_attr() takes the page-table spinlock around a read-modify-write operation even though pte_update() already makes that update atomic, causing recursive lock acquisition. The flaw requires local low-privileged access on a PowerPC kernel and can deny service without disclosing or modifying data.

The record

CVE
CVE-2021-47632
Published
Feb 26, 2025
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-667, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 26, 2025CVE 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=1f9ad21c3b384a8f16d8c46845a48a01d281a603 <6def4eaf0391f24be541633a954c0e4876858b1e
  2. Affected versionversion=1f9ad21c3b384a8f16d8c46845a48a01d281a603 <6ebe5ca2cbe438a688f2ae238ef5a0b0b5f3468a
  3. Affected versionversion=1f9ad21c3b384a8f16d8c46845a48a01d281a603 <96917107e67846f1d959ed03be281048efad14c5
  4. Affected versionversion=1f9ad21c3b384a8f16d8c46845a48a01d281a603 <a4c182ecf33584b9b2d1aa9dad073014a504c01f
  5. Affected versionversion=5.14

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=1f9ad21c3b384a8f16d8c46845a48a01d281a603 <6def4eaf0391f24be541633a954c0e4876858b1e; version=1f9ad21c3b384a8f16d8c46845a48a01d281a603 <6ebe5ca2cbe438a688f2ae238ef5a0b0b5f3468a; version=1f9ad21c3b384a8f16d8c46845a48a01d281a603 <96917107e67846f1d959ed03be281048efad14c5; version=1f9ad21c3b384a8f16d8c46845a48a01d281a603 <a4c182ecf33584b9b2d1aa9dad073014a504c01f; version=5.14

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5CISA-ADPCVSS: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-667Improper Locking
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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