CVE-2021-47072

Filesystem inconsistency via incomplete rename logging

Published Mar 1, 2024 · Updated May 11, 2026

Btrfs directory logging in Linux 5.12 before 5.12.7 allows local users to leave stale dentries after power-loss recovery. During a logged rename, tree-log.c records the new name without forcing the old parent log to cover the old dentry's DIR_ITEM and DIR_INDEX keys. The condition requires a specific Btrfs key layout, logged parent and inode, rename, log sync, and subsequent power failure; replay can retain an obsolete file link or reject a directory tree and prevent mounting.

CVSS severity5.5
Medium
EPSS probability0.19%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Btrfs directory logging in Linux 5.12 before 5.12.7 allows local users to leave stale dentries after power-loss recovery. During a logged rename, tree-log.c records the new name without forcing the old parent log to cover the old dentry's DIR_ITEM and DIR_INDEX keys. The condition requires a specific Btrfs key layout, logged parent and inode, rename, log sync, and subsequent power failure; replay can retain an obsolete file link or reject a directory tree and prevent mounting.

The record

CVE
CVE-2021-47072
Published
Mar 1, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 1, 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=5.12
  2. Affected versionversion=64d6b281ba4db044c946158387c74e1149b9487e <54a40fc3a1da21b52dbf19f72fdc27a2ec740760
  3. Affected versionversion=64d6b281ba4db044c946158387c74e1149b9487e <6d0924c5b742036b4f20a0ffdf2b6cf3f963f5f6

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.12; version=64d6b281ba4db044c946158387c74e1149b9487e <54a40fc3a1da21b52dbf19f72fdc27a2ec740760; version=64d6b281ba4db044c946158387c74e1149b9487e <6d0924c5b742036b4f20a0ffdf2b6cf3f963f5f6

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 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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