CVE-2026-89595

Notification loss via concurrent mark updates

Published Sep 11, 2026 · Updated Sep 11, 2026

A race in Linux fsnotify allows local users to make fanotify and inotify clients miss file-modification events via concurrent mark updates. In fanotify_mark_add_to_mask and the inotify watch-replacement path, concurrent scans can publish an aggregate object mask that omits a newly added event bit. Triggering the condition requires concurrent updates to separate marks on the same inode; the stale mask then suppresses FAN_MODIFY or IN_MODIFY delivery after both updates finish.

CVSS severityUnavailable
Unscored
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

A race in Linux fsnotify allows local users to make fanotify and inotify clients miss file-modification events via concurrent mark updates. In fanotify_mark_add_to_mask and the inotify watch-replacement path, concurrent scans can publish an aggregate object mask that omits a newly added event bit. Triggering the condition requires concurrent updates to separate marks on the same inode; the stale mask then suppresses FAN_MODIFY or IN_MODIFY delivery after both updates finish.

The record

CVE
CVE-2026-89595
Published
Sep 11, 2026
Updated
Sep 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1562.001
Attack vector
local
Privileges
Unavailable

Timeline

How it unfolded

  1. Sep 11, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 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=2.6.31
  2. Affected versionversion=63c882a05416e18de6fb59f7dd6da48f3bbe8273 <947400af98b9e63841929d079a2c3ea0a8ba227b
  3. Affected versionversion=63c882a05416e18de6fb59f7dd6da48f3bbe8273 <ac8d8b599d466a129122bded77db3d0f8b96b461
  4. Affected versionversion=63c882a05416e18de6fb59f7dd6da48f3bbe8273 <e422777fdd4746de1109575c51e65038d4c5c1be

What conditions does exploitation require?

Attack vectorlocal
Required privilegesUnavailable in this record.

What is affected?

The Linux Kernel Organization · Linuxversion=2.6.31; version=63c882a05416e18de6fb59f7dd6da48f3bbe8273 <947400af98b9e63841929d079a2c3ea0a8ba227b; version=63c882a05416e18de6fb59f7dd6da48f3bbe8273 <ac8d8b599d466a129122bded77db3d0f8b96b461; version=63c882a05416e18de6fb59f7dd6da48f3bbe8273 <e422777fdd4746de1109575c51e65038d4c5c1be

Published CVSS scores

No CVSS assessment is available in this record.

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
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1562.001Impair Defenses: Disable or Modify Tools

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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