CVE-2025-71269Network attack vector

Service outage via premature qgroup reservation release

Published Mar 18, 2026 · Updated Mar 18, 2026

Resource accounting error in Btrfs in Linux Kernel allows remote attackers to exhaust filesystem capacity via file writes. __cow_file_range_inline() releases reserved qgroup data after inline extent creation fails with -ENOSPC, then the fallback COW path consumes data without retaining that reservation. A guest-writable SMB share or anonymously writable NFS export backed by Btrfs must permit repeated small-file writes; exhaustion causes persistent ENOSPC failures and service outage.

CVSS severity7.5
High
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

Resource accounting error in Btrfs in Linux Kernel allows remote attackers to exhaust filesystem capacity via file writes. __cow_file_range_inline() releases reserved qgroup data after inline extent creation fails with -ENOSPC, then the fallback COW path consumes data without retaining that reservation. A guest-writable SMB share or anonymously writable NFS export backed by Btrfs must permit repeated small-file writes; exhaustion causes persistent ENOSPC failures and service outage.

The record

CVE
CVE-2025-71269
Published
Mar 18, 2026
Updated
Mar 18, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 18, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 18, 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=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <6de3a371a8b9fd095198b1aa68c22cc10a4c6961
  2. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <f8da41de0bff9eb1d774a7253da0c9f637c4470a

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <6de3a371a8b9fd095198b1aa68c22cc10a4c6961; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <f8da41de0bff9eb1d774a7253da0c9f637c4470a

Published CVSS scores

7.5Linux Kernel CNACVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
4.7SUSECVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.7SUSECVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
5.5UbuntuCVSS: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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Application or System Exploitation

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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