CVE-2026-64392
Received Received - Intake

ksmbd Credential Handling Flaw Enables Permission Bypass

Publication date: 2026-07-25

Last updated on: 2026-07-25

Assigner: kernel.org

Description
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.

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Meta Information

Published
2026-07-25
Last Modified
2026-07-25
Generated
2026-07-25
AI Q&A
2026-07-25
EPSS Evaluated
N/A
NVD
CVE-2026-64392
EUVD
EUVD-2026-48936

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux_kernel ksmbd *

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Exploitability

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KEV
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel's ksmbd component allows a user to bypass filesystem permission checks when performing delete-on-close operations. Normally, these operations should respect the user's permissions, but due to a flaw, they run with the worker credentials instead of the authenticated user's credentials.

Impact Analysis

An attacker with access to a system using ksmbd could potentially delete or modify files they do not have permission to access. This could lead to unauthorized data loss, corruption, or exposure, depending on the system's configuration and the attacker's goals.

Compliance Impact

This vulnerability could lead to unauthorized access or deletion of sensitive data, violating compliance requirements such as GDPR's data integrity and confidentiality principles or HIPAA's safeguards for protected health information. Organizations using affected systems may face compliance violations and legal consequences.

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