CVE-2026-45942

Filesystem corruption via unlocked buddy fast path

Published May 27, 2026 · Updated May 27, 2026

Race condition in Linux Kernel ext4 allows local users to corrupt filesystem allocation state through block allocation and page migration. The ext4_mb_load_buddy fast path merely increments a folio reference and uses an uptodate buddy folio without locking it, so migration can overlap bitmap writes. Low-privilege access to an ext4 filesystem is sufficient, but exploitation requires sustained allocation I/O and memory pressure that induce the narrow migration race.

CVSS severity7.8
High
EPSS probability0.10%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Race condition in Linux Kernel ext4 allows local users to corrupt filesystem allocation state through block allocation and page migration. The ext4_mb_load_buddy fast path merely increments a folio reference and uses an uptodate buddy folio without locking it, so migration can overlap bitmap writes. Low-privilege access to an ext4 filesystem is sufficient, but exploitation requires sustained allocation I/O and memory pressure that induce the narrow migration race.

The record

CVE
CVE-2026-45942
Published
May 27, 2026
Updated
May 27, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
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=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 <29a07d691d282faf38c33d4b61839b89399110f9
  6. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <57e83bfbe1e412ac42daced2086f3c6f9a17bba0
  7. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <bdc56a9c46b2a99c12313122b9352b619a2e719e
  8. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <c05033cfc5c7699cd4df8d48cef94d01da755f24
  9. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <f29709a7a3fc38f5015d850504762cdef0e151f9

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 <29a07d691d282faf38c33d4b61839b89399110f9; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <57e83bfbe1e412ac42daced2086f3c6f9a17bba0; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <bdc56a9c46b2a99c12313122b9352b619a2e719e; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <c05033cfc5c7699cd4df8d48cef94d01da755f24; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <f29709a7a3fc38f5015d850504762cdef0e151f9

Published CVSS scores

7.8Linux Kernel CVE TeamCVSS: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 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

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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