CVE-2026-45920

Filesystem accounting corruption via dirtyclusters double decrement

Published May 27, 2026 · Updated May 27, 2026

Counter-management error in Linux Kernel ext4 allows local users to corrupt filesystem allocation accounting during shutdown. When ext4_mb_mark_context returns an error after changing metadata, ext4_mb_mark_diskspace_used decrements the dirty-cluster reservation before ext4_mb_new_blocks decrements it again on the !ar->len path. Triggering requires an ext4 shutdown to interrupt allocation after metadata changed, leaving s_dirtyclusters_counter negative and causing an ext4_put_super warning.

CVSS severity7.8
High
EPSS probability0.15%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Counter-management error in Linux Kernel ext4 allows local users to corrupt filesystem allocation accounting during shutdown. When ext4_mb_mark_context returns an error after changing metadata, ext4_mb_mark_diskspace_used decrements the dirty-cluster reservation before ext4_mb_new_blocks decrements it again on the !ar->len path. Triggering requires an ext4 shutdown to interrupt allocation after metadata changed, leaving s_dirtyclusters_counter negative and causing an ext4_put_super warning.

The record

CVE
CVE-2026-45920
Published
May 27, 2026
Updated
May 27, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-415, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 27, 2026CVE publishedPublication date reported by the CVE source.
  2. May 27, 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=0087d9fb3f29f59e8d42c8b058376d80e5adde4c <3924aea2c33df3864929c1acd178bfc29d8f005f
  2. Affected versionversion=0087d9fb3f29f59e8d42c8b058376d80e5adde4c <523d5a4df3c649fa305c89efb552ec62a1ce9d3d
  3. Affected versionversion=0087d9fb3f29f59e8d42c8b058376d80e5adde4c <55576fa14771d33994c29a9ae960e07bb3f56c20
  4. Affected versionversion=0087d9fb3f29f59e8d42c8b058376d80e5adde4c <61e372122b6d95aec940fdaea0a16f988f359897
  5. Affected versionversion=0087d9fb3f29f59e8d42c8b058376d80e5adde4c <81982a11406c5da6c6e2b188028e7056e16b7128
  6. Affected versionversion=0087d9fb3f29f59e8d42c8b058376d80e5adde4c <94a8cea54cd935c54fa2fba70354757c0fc245e3
  7. Affected versionversion=0087d9fb3f29f59e8d42c8b058376d80e5adde4c <ca408af08544d96769c93a3d81a7f63f61129e95
  8. Affected versionversion=0087d9fb3f29f59e8d42c8b058376d80e5adde4c <dbc4e10619ed87a50e637b96f2e574df36a7a769
  9. Affected versionversion=2.6.29

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=0087d9fb3f29f59e8d42c8b058376d80e5adde4c <3924aea2c33df3864929c1acd178bfc29d8f005f; version=0087d9fb3f29f59e8d42c8b058376d80e5adde4c <523d5a4df3c649fa305c89efb552ec62a1ce9d3d; version=0087d9fb3f29f59e8d42c8b058376d80e5adde4c <55576fa14771d33994c29a9ae960e07bb3f56c20; version=0087d9fb3f29f59e8d42c8b058376d80e5adde4c <61e372122b6d95aec940fdaea0a16f988f359897; version=0087d9fb3f29f59e8d42c8b058376d80e5adde4c <81982a11406c5da6c6e2b188028e7056e16b7128; version=0087d9fb3f29f59e8d42c8b058376d80e5adde4c <94a8cea54cd935c54fa2fba70354757c0fc245e3; version=0087d9fb3f29f59e8d42c8b058376d80e5adde4c <ca408af08544d96769c93a3d81a7f63f61129e95; version=0087d9fb3f29f59e8d42c8b058376d80e5adde4c <dbc4e10619ed87a50e637b96f2e574df36a7a769; version=2.6.29

Published CVSS scores

4.7Amazon LinuxCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5OracleCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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

CWE-415Double Free
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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