CVE-2021-47433

Filesystem corruption via incorrect extent-replacement abort logic

Published May 22, 2024 · Updated Aug 5, 2026

Improper error handling in the Linux btrfs extent-replacement path allows local users to corrupt a mounted filesystem. btrfs_replace_file_extents combines the clone-path flag with the return code incorrectly, so preallocation errors can escape the required transaction abort and leave a missing extent. Reachability requires local access that exercises preallocation on a btrfs filesystem while an underlying operation fails; the documented consequence is filesystem corruption rather than code execution.

CVSS severity5.5
Medium
EPSS probability0.57%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper error handling in the Linux btrfs extent-replacement path allows local users to corrupt a mounted filesystem. btrfs_replace_file_extents combines the clone-path flag with the return code incorrectly, so preallocation errors can escape the required transaction abort and leave a missing extent. Reachability requires local access that exercises preallocation on a btrfs filesystem while an underlying operation fails; the documented consequence is filesystem corruption rather than code execution.

The record

CVE
CVE-2021-47433
Published
May 22, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1485
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=5.10
  2. Affected versionversion=8fccebfa534c7984864394fa03608305e4929aae <0e309e1152fc34ef75991d9d69b165dbf75bf26c
  3. Affected versionversion=8fccebfa534c7984864394fa03608305e4929aae <0e32a2b85c7d92ece86c17dfef390c5ed79c6378
  4. Affected versionversion=8fccebfa534c7984864394fa03608305e4929aae <4afb912f439c4bc4e6a4f3e7547f2e69e354108f

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.10; version=8fccebfa534c7984864394fa03608305e4929aae <0e309e1152fc34ef75991d9d69b165dbf75bf26c; version=8fccebfa534c7984864394fa03608305e4929aae <0e32a2b85c7d92ece86c17dfef390c5ed79c6378; version=8fccebfa534c7984864394fa03608305e4929aae <4afb912f439c4bc4e6a4f3e7547f2e69e354108f

Published CVSS scores

5.5CanonicalCVSS: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

T1485Data Destruction

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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