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Review reviewCritical

CVE-2026-64392

Linux

In the Linux kernel, the following vulnerability has been resolved: ksmbd: use opener credentials for delete-on-close Delete-on-close can be completed by deferred or durable handle teardown, where no request work is available. Both the base-file unlink and the ADS xattr removal consequently run with the ksmbd worker credentials and can bypass filesystem permission checks. Run both operations with the credentials captured in struct file when the handle was opened. This preserves the authenticated user's fsuid, fsgid, supplementary groups and capability restrictions at final close.

CVSS
9.1
EPSS
-
- percentile
CISA KEV
Not listed
Published
2026.07.25
PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability-
Technical severityCVSS 9.1

Vulnerability overview

In the Linux kernel, the following vulnerability has been resolved: ksmbd: use opener credentials for delete-on-close Delete-on-close can be completed by deferred or durable handle teardown, where no request work is available. Both the base-file unlink and the ADS xattr removal consequently run with the ksmbd worker credentials and can bypass filesystem permission checks. Run both operations with the credentials captured in struct file when the handle was opened. This preserves the authenticated user's fsuid, fsgid, supplementary groups and capability restrictions at final close.

Affected product and versions

Product
Linux
Affected versions
>= f44158485826c076335d6860d35872271a83791d < f08b3f451f12eee4abd8a5981803bc36db84458b, >= f44158485826c076335d6860d35872271a83791d < 18c59109bb6fb816d5102171666f87cf1e29901d, >= f44158485826c076335d6860d35872271a83791d < e72c15085b6d86f45d224d98aa75b5cace4aaab9, >= f44158485826c076335d6860d35872271a83791d < 4b7059974549d278e30fe70e2a4e421f9839817d, >= f44158485826c076335d6860d35872271a83791d < 52e2f21911158ec961cd5aae19c56460db382af0, >= 5.15
Fixed versions
No verified fixed-version field is available yet

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that Linux and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
CWE
Not available