CVE-2026-45858

Local stale-data disclosure via failed extent split

Published May 27, 2026 · Updated May 27, 2026

Stale-data exposure in Linux Kernel ext4 allows local users to read prior block contents when a large unwritten extent is split. The ext4_split_extent() path marks the entire extent written after ext4_split_extent_at() cannot split at the second boundary, leaving the prefix backed by stale disk data. Triggering requires low local privileges, an ext4 operation that splits a large unwritten extent, and temporary space exhaustion during the first split.

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

What happened

Stale-data exposure in Linux Kernel ext4 allows local users to read prior block contents when a large unwritten extent is split. The ext4_split_extent() path marks the entire extent written after ext4_split_extent_at() cannot split at the second boundary, leaving the prefix backed by stale disk data. Triggering requires low local privileges, an ext4 operation that splits a large unwritten extent, and temporary space exhaustion during the first split.

The record

CVE
CVE-2026-45858
Published
May 27, 2026
Updated
May 27, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1005
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=0 <6.12.75
  2. Affected versionversion=0 <6.18.14
  3. Affected versionversion=0 <6.19.4
  4. Affected versionversion=0 <6.6.130
  5. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <1bf6974822d1dba86cf11b5f05498581cf3488a2
  6. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <58ddae5d77b1db3a27b891c75a8fa120239ac092
  7. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <7015fcf473796e1d2d876f241bd9e0c36f3d4eef
  8. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <d17857b4fb9ba5745b59be0ef38fd532991fccbf
  9. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <d67c8ecf3d8fda9b8ef80e6f665d84b6d6ac9d88

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=0 <6.12.75; version=0 <6.18.14; version=0 <6.19.4; version=0 <6.6.130; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <1bf6974822d1dba86cf11b5f05498581cf3488a2; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <58ddae5d77b1db3a27b891c75a8fa120239ac092; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <7015fcf473796e1d2d876f241bd9e0c36f3d4eef; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <d17857b4fb9ba5745b59be0ef38fd532991fccbf; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <d67c8ecf3d8fda9b8ef80e6f665d84b6d6ac9d88

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1005Data from Local System

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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