CVE-2026-90265Hinoki check available

Filesystem hang via defragmentation reservation deadlock

Published Sep 17, 2026 · Updated Sep 17, 2026

Deadlock in Btrfs defragmentation in Linux Foundation Linux Kernel allows local users to hang filesystem operations via file activity. In fs/btrfs/defrag.c, defrag_one_range reserves delayed-allocation space while holding dirty folios and extent locks, blocking reclaim that needs those locks. The observed path uses autodefrag under metadata pressure; flushoncommit is not required, and writeback and reclaim tasks hang.

CVSS severity4.7
Medium
EPSS probability0.21%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Deadlock in Btrfs defragmentation in Linux Foundation Linux Kernel allows local users to hang filesystem operations via file activity. In fs/btrfs/defrag.c, defrag_one_range reserves delayed-allocation space while holding dirty folios and extent locks, blocking reclaim that needs those locks. The observed path uses autodefrag under metadata pressure; flushoncommit is not required, and writeback and reclaim tasks hang.

The record

CVE
CVE-2026-90265
Published
Sep 17, 2026
Updated
Sep 17, 2026
Vendor
Linux Foundation
Product
Linux Kernel
Classifications
T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 17, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 17, 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=22b398eeeed43d51e85b1008e51bf9663ac1f491 <a9701dd06e82c345fe70debdf8835b7eb5000c59
  2. Affected versionversion=22b398eeeed43d51e85b1008e51bf9663ac1f491 <ac916391e1c70801649f7d6f85014f687983bc33
  3. Affected versionversion=22b398eeeed43d51e85b1008e51bf9663ac1f491 <ba02eab28041f9a4bbe9fc90c7249644fef6de0f
  4. Affected versionversion=5.16

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Linux Foundation · Linux Kernelversion=22b398eeeed43d51e85b1008e51bf9663ac1f491 <a9701dd06e82c345fe70debdf8835b7eb5000c59; version=22b398eeeed43d51e85b1008e51bf9663ac1f491 <ac916391e1c70801649f7d6f85014f687983bc33; version=22b398eeeed43d51e85b1008e51bf9663ac1f491 <ba02eab28041f9a4bbe9fc90c7249644fef6de0f; version=5.16

Published CVSS scores

4.7Amazon LinuxCVSS:3.1/AV:L/AC:H/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.

Activity data is delayed. The latest report is Sep 28, 2026.

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

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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