CVE-2026-74318

Filesystem hang via missed inline-extent size update

Published Aug 15, 2026 · Updated Aug 15, 2026

Deadlock in the Btrfs reflink path in Linux 5.7 and later allows local users to hang filesystem writeback by cloning inline extents. For a nonzero destination offset, the clone path fails to update i_size after copying inline extent data, leaving writeback and transaction commit waiting on conflicting extent state. Reachability requires local file operations on a Btrfs filesystem mounted with flushoncommit; the observed consequence is blocked writeback and filesystem operations, not data disclosure or modification.

CVSS severity5.5
Medium
EPSS probability0.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Deadlock in the Btrfs reflink path in Linux 5.7 and later allows local users to hang filesystem writeback by cloning inline extents. For a nonzero destination offset, the clone path fails to update i_size after copying inline extent data, leaving writeback and transaction commit waiting on conflicting extent state. Reachability requires local file operations on a Btrfs filesystem mounted with flushoncommit; the observed consequence is blocked writeback and filesystem operations, not data disclosure or modification.

The record

CVE
CVE-2026-74318
Published
Aug 15, 2026
Updated
Aug 15, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 15, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 15, 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=05a5a7621ce66c142e081ffc24dd6ade6e912061 <06283034cec0fa357cbd85784ef7d3f5b2ce0790
  2. Affected versionversion=05a5a7621ce66c142e081ffc24dd6ade6e912061 <2aa37c8ef1092c6f088e23a90bffefc672831c09
  3. Affected versionversion=05a5a7621ce66c142e081ffc24dd6ade6e912061 <532085d00eb54c074bdeae648b194765239f4d11
  4. Affected versionversion=05a5a7621ce66c142e081ffc24dd6ade6e912061 <ea3452726ccb6bcaa732f43cc57bb928eca3dd59
  5. Affected versionversion=5.7

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=05a5a7621ce66c142e081ffc24dd6ade6e912061 <06283034cec0fa357cbd85784ef7d3f5b2ce0790; version=05a5a7621ce66c142e081ffc24dd6ade6e912061 <2aa37c8ef1092c6f088e23a90bffefc672831c09; version=05a5a7621ce66c142e081ffc24dd6ade6e912061 <532085d00eb54c074bdeae648b194765239f4d11; version=05a5a7621ce66c142e081ffc24dd6ade6e912061 <ea3452726ccb6bcaa732f43cc57bb928eca3dd59; version=5.7

Published CVSS scores

4.7Amazon LinuxCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5Oracle LinuxCVSS: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

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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