CVE-2026-64298

Unauthorized NFS file truncation via incomplete permission mask

Published Jul 25, 2026 · Updated Jul 25, 2026

Improper authorization in Linux Kernel NFSv4 allows local users to truncate protected files through O_RDONLY|O_TRUNC opens. nfs_open_permission_mask() derives access solely from O_ACCMODE, omits MAY_WRITE for O_TRUNC, and lets a cached write delegation issue SETATTR(size=0). Ordinary local access plus read and path-search permission is sufficient; successful exploitation destroys the target file's contents and can interrupt dependent services.

CVSS severity7.1
High
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 authorization in Linux Kernel NFSv4 allows local users to truncate protected files through O_RDONLY|O_TRUNC opens. nfs_open_permission_mask() derives access solely from O_ACCMODE, omits MAY_WRITE for O_TRUNC, and lets a cached write delegation issue SETATTR(size=0). Ordinary local access plus read and path-search permission is sufficient; successful exploitation destroys the target file's contents and can interrupt dependent services.

The record

CVE
CVE-2026-64298
Published
Jul 25, 2026
Updated
Jul 25, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1485
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=2.6.24
  2. Affected versionversion=af22f94ae02ab9dd4fd7fe628c8434a59cc293be <22c1fd1355ad4ca27aa7f0fa02719122dd92d9de
  3. Affected versionversion=af22f94ae02ab9dd4fd7fe628c8434a59cc293be <30fdf4df6c3c00efec947e4ddf97f0fdd4473628
  4. Affected versionversion=af22f94ae02ab9dd4fd7fe628c8434a59cc293be <4817c8974315b666e895b7d1bb83cd3664c323b1
  5. Affected versionversion=af22f94ae02ab9dd4fd7fe628c8434a59cc293be <5140f099ecd8a2f2808b7f7b720ee1bad8468974
  6. Affected versionversion=af22f94ae02ab9dd4fd7fe628c8434a59cc293be <6bd7d0a06b53c4e797e1a9cea0d2d41aa1b26230
  7. Affected versionversion=af22f94ae02ab9dd4fd7fe628c8434a59cc293be <a937e92c1d00534b5c2e3e9f4381b7e988180797
  8. Affected versionversion=af22f94ae02ab9dd4fd7fe628c8434a59cc293be <cb148a2762d644bff1894728e8835a9a4b84f9ea
  9. Affected versionversion=af22f94ae02ab9dd4fd7fe628c8434a59cc293be <e36501b7d4abdcd6d69a7cb901b2f286b7a3d041

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=2.6.24; version=af22f94ae02ab9dd4fd7fe628c8434a59cc293be <22c1fd1355ad4ca27aa7f0fa02719122dd92d9de; version=af22f94ae02ab9dd4fd7fe628c8434a59cc293be <30fdf4df6c3c00efec947e4ddf97f0fdd4473628; version=af22f94ae02ab9dd4fd7fe628c8434a59cc293be <4817c8974315b666e895b7d1bb83cd3664c323b1; version=af22f94ae02ab9dd4fd7fe628c8434a59cc293be <5140f099ecd8a2f2808b7f7b720ee1bad8468974; version=af22f94ae02ab9dd4fd7fe628c8434a59cc293be <6bd7d0a06b53c4e797e1a9cea0d2d41aa1b26230; version=af22f94ae02ab9dd4fd7fe628c8434a59cc293be <a937e92c1d00534b5c2e3e9f4381b7e988180797; version=af22f94ae02ab9dd4fd7fe628c8434a59cc293be <cb148a2762d644bff1894728e8835a9a4b84f9ea; version=af22f94ae02ab9dd4fd7fe628c8434a59cc293be <e36501b7d4abdcd6d69a7cb901b2f286b7a3d041

Published CVSS scores

7.1kernel.orgCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/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

T1485Data Destruction

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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