CVE-2021-47510

Forced read-only filesystem via missed node re-dirty

Published May 24, 2024 · Updated May 11, 2026

Denial of service in Linux 5.12 through 5.15.7 allows local users to force a zoned Btrfs filesystem read-only during sustained reads. In fs/btrfs/tree-log.c, upward tree-log walking fails to re-dirty a freed node when the log depth is at least two, leaving a write hole. A mounted zoned Btrfs filesystem and local I/O access are required; the resulting -EAGAIN transaction abort stops writes without disclosing or modifying data.

CVSS severity5.5
Medium
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

Denial of service in Linux 5.12 through 5.15.7 allows local users to force a zoned Btrfs filesystem read-only during sustained reads. In fs/btrfs/tree-log.c, upward tree-log walking fails to re-dirty a freed node when the log depth is at least two, leaving a write hole. A mounted zoned Btrfs filesystem and local I/O access are required; the resulting -EAGAIN transaction abort stops writes without disclosing or modifying data.

The record

CVE
CVE-2021-47510
Published
May 24, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 24, 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=d3575156f6623eecf086a20bcf99a63f1598109c <477675049ca803aa95ff77468ffbddd966b415b0
  3. Affected versionversion=d3575156f6623eecf086a20bcf99a63f1598109c <84c25448929942edacba905cecc0474e91114e7a

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.12; version=d3575156f6623eecf086a20bcf99a63f1598109c <477675049ca803aa95ff77468ffbddd966b415b0; version=d3575156f6623eecf086a20bcf99a63f1598109c <84c25448929942edacba905cecc0474e91114e7a

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.

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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.

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Technologies

Your stack

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Your stack

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