CVE-2026-64294

Local operation denial via wrong mount idmap

Published Jul 25, 2026 · Updated Jul 25, 2026

Improper ownership validation in Linux Kernel 5.12 and later causes local users' mincore() and MADV_PAGEOUT requests to fail. The affected memory-management paths pass nop_mnt_idmap to owner_or_capable(), so translated mount ownership is ignored and the mapped owner is rejected. Triggering the error requires an idmapped mount and a file, such as a 0444 file, for which the fallback write-permission check fails.

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

Improper ownership validation in Linux Kernel 5.12 and later causes local users' mincore() and MADV_PAGEOUT requests to fail. The affected memory-management paths pass nop_mnt_idmap to owner_or_capable(), so translated mount ownership is ignored and the mapped owner is rejected. Triggering the error requires an idmapped mount and a file, such as a 0444 file, for which the fallback write-permission check fails.

The record

CVE
CVE-2026-64294
Published
Jul 25, 2026
Updated
Jul 25, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-283
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 25, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 25, 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=5.12
  2. Affected versionversion=9caccd41541a6f7d6279928d9f971f6642c361af <04ba248d02d9eaa3d9077b00a6134caa75fa3e90
  3. Affected versionversion=9caccd41541a6f7d6279928d9f971f6642c361af <5c942ad7df75925ee166e7f0fb36892d8dde376b
  4. Affected versionversion=9caccd41541a6f7d6279928d9f971f6642c361af <744b23aa430d52f5c8e4dbff7d71496d6643bed2
  5. Affected versionversion=9caccd41541a6f7d6279928d9f971f6642c361af <8344bdf0629457e532797b42d9d2bbf2a2900bbf
  6. Affected versionversion=9caccd41541a6f7d6279928d9f971f6642c361af <e187bc02f8fa4226d62814592cf064ee4557c470

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=5.12; version=9caccd41541a6f7d6279928d9f971f6642c361af <04ba248d02d9eaa3d9077b00a6134caa75fa3e90; version=9caccd41541a6f7d6279928d9f971f6642c361af <5c942ad7df75925ee166e7f0fb36892d8dde376b; version=9caccd41541a6f7d6279928d9f971f6642c361af <744b23aa430d52f5c8e4dbff7d71496d6643bed2; version=9caccd41541a6f7d6279928d9f971f6642c361af <8344bdf0629457e532797b42d9d2bbf2a2900bbf; version=9caccd41541a6f7d6279928d9f971f6642c361af <e187bc02f8fa4226d62814592cf064ee4557c470

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

CWE-283Unverified Ownership

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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