CVE-2026-43065

Service interrupt via undrained ext4 discard work

Published May 5, 2026 · Updated May 5, 2026

Denial of service in Linux Kernel ext4 allows local users to interrupt the system by racing queued discard work against filesystem unmount. ext4_mb_release() flushes s_discard_work only while EXT4_MOUNT_DISCARD remains set, so a nodiscard remount can leave previously queued work undrained. The race requires a discard mount, mass file deletion, a nodiscard remount, and immediate unmount before the work drains naturally; no data disclosure or modification is reported.

CVSS severity5.5
Medium
EPSS probability0.12%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Linux Kernel ext4 allows local users to interrupt the system by racing queued discard work against filesystem unmount. ext4_mb_release() flushes s_discard_work only while EXT4_MOUNT_DISCARD remains set, so a nodiscard remount can leave previously queued work undrained. The race requires a discard mount, mass file deletion, a nodiscard remount, and immediate unmount before the work drains naturally; no data disclosure or modification is reported.

The record

CVE
CVE-2026-43065
Published
May 5, 2026
Updated
May 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 5, 2026CVE publishedPublication date reported by the CVE source.
  2. May 5, 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=5.15
  2. Affected versionversion=55cdd0af2bc5ffc92a2deb745627755aecd5db33 <1c82f863f090ab899085bdfade073313384b514b
  3. Affected versionversion=55cdd0af2bc5ffc92a2deb745627755aecd5db33 <812b6a7cd3e7f3a3e8a24db85bc6313c26cb1098
  4. Affected versionversion=55cdd0af2bc5ffc92a2deb745627755aecd5db33 <9b4d9dda6a71ad3425c8109d27c4c6bfb9da97b8
  5. Affected versionversion=55cdd0af2bc5ffc92a2deb745627755aecd5db33 <9ee29d20aab228adfb02ca93f87fb53c56c2f3af
  6. Affected versionversion=55cdd0af2bc5ffc92a2deb745627755aecd5db33 <b4737e26d4688b8aea88ad6ea4dbfeb6e78b0327
  7. Affected versionversion=55cdd0af2bc5ffc92a2deb745627755aecd5db33 <c360e9d0def4f4ae03254a67c683103908555b75
  8. Affected versionversion=55cdd0af2bc5ffc92a2deb745627755aecd5db33 <e96c2354b170aaa53300c8e8fd59e41b133160f7

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=5.15; version=55cdd0af2bc5ffc92a2deb745627755aecd5db33 <1c82f863f090ab899085bdfade073313384b514b; version=55cdd0af2bc5ffc92a2deb745627755aecd5db33 <812b6a7cd3e7f3a3e8a24db85bc6313c26cb1098; version=55cdd0af2bc5ffc92a2deb745627755aecd5db33 <9b4d9dda6a71ad3425c8109d27c4c6bfb9da97b8; version=55cdd0af2bc5ffc92a2deb745627755aecd5db33 <9ee29d20aab228adfb02ca93f87fb53c56c2f3af; version=55cdd0af2bc5ffc92a2deb745627755aecd5db33 <b4737e26d4688b8aea88ad6ea4dbfeb6e78b0327; version=55cdd0af2bc5ffc92a2deb745627755aecd5db33 <c360e9d0def4f4ae03254a67c683103908555b75; version=55cdd0af2bc5ffc92a2deb745627755aecd5db33 <e96c2354b170aaa53300c8e8fd59e41b133160f7

Published CVSS scores

5.5NIST NVDCVSS: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

T1499.004Endpoint Denial of Service

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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