CVE-2021-47034

Kernel crash via unsynchronized radix PTE update

Published Feb 28, 2024 · Updated May 11, 2026

A page-table ordering flaw in Linux 4.18 through 5.12 allows local users with administrative privileges to crash PowerPC systems. The map_kernel_page() path omits flush_cache_vmap(), so a new radix PTE is not ordered with ptesync before do_patch_instruction() writes through it. Reachability requires privileged code-patching activity on 64-bit PowerPC radix systems with Strict RWX, where the unhandled fault can panic the kernel.

CVSS severity4.4
Medium
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A page-table ordering flaw in Linux 4.18 through 5.12 allows local users with administrative privileges to crash PowerPC systems. The map_kernel_page() path omits flush_cache_vmap(), so a new radix PTE is not ordered with ptesync before do_patch_instruction() writes through it. Reachability requires privileged code-patching activity on 64-bit PowerPC radix systems with Strict RWX, where the unhandled fault can panic the kernel.

The record

CVE
CVE-2021-47034
Published
Feb 28, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
local
Privileges
admin

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

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=4.18
  2. Affected versionversion=f1cb8f9beba8699dd1b4518418191499e53f7b17 <01ac203e2119d8922126886ddea309fb676f955f
  3. Affected versionversion=f1cb8f9beba8699dd1b4518418191499e53f7b17 <73f9dccb29e4f82574bec2765c0090cdb0404301
  4. Affected versionversion=f1cb8f9beba8699dd1b4518418191499e53f7b17 <84c0762633f2a7ac8399e6b97d3b9bb8e6e1d50f
  5. Affected versionversion=f1cb8f9beba8699dd1b4518418191499e53f7b17 <b3d5d0983388d6c4fb35f7d722556d5595f167a7
  6. Affected versionversion=f1cb8f9beba8699dd1b4518418191499e53f7b17 <b8b2f37cf632434456182e9002d63cbc4cccc50c
  7. Affected versionversion=f1cb8f9beba8699dd1b4518418191499e53f7b17 <e40c52ee67b155ad59f59e73ea136d02685f0e0d

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

The Linux Kernel Organization · Linuxversion=4.18; version=f1cb8f9beba8699dd1b4518418191499e53f7b17 <01ac203e2119d8922126886ddea309fb676f955f; version=f1cb8f9beba8699dd1b4518418191499e53f7b17 <73f9dccb29e4f82574bec2765c0090cdb0404301; version=f1cb8f9beba8699dd1b4518418191499e53f7b17 <84c0762633f2a7ac8399e6b97d3b9bb8e6e1d50f; version=f1cb8f9beba8699dd1b4518418191499e53f7b17 <b3d5d0983388d6c4fb35f7d722556d5595f167a7; version=f1cb8f9beba8699dd1b4518418191499e53f7b17 <b8b2f37cf632434456182e9002d63cbc4cccc50c; version=f1cb8f9beba8699dd1b4518418191499e53f7b17 <e40c52ee67b155ad59f59e73ea136d02685f0e0d

Published CVSS scores

4.4UbuntuCVSS:3.1/AV:L/AC:L/PR:H/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
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

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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