CVE-2026-64391
Received Received - Intake

BaseFortify

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 ADS I/O Alternate data streams are stored as xattrs. Unlike regular file I/O, their read and write paths therefore call VFS xattr helpers which recheck inode permissions and LSM policy using the current task credentials. Run ADS I/O with the credentials captured when the SMB handle was opened.

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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-2026-64391
EUVD
EUVD-2026-48935

Affected Vendors & Products

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

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Exploitability

CWE
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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 involves ksmbd, a server implementing the SMB/CIFS protocol. It allows alternate data streams (ADS) to be stored as extended attributes (xattrs). When reading or writing ADS, the kernel uses VFS xattr helpers that recheck permissions and security policies using the current task's credentials. The fix ensures ADS I/O operations use the credentials captured when the SMB handle was opened, preventing unauthorized access.

Impact Analysis

If exploited, this vulnerability could allow an attacker to bypass intended permission checks on ADS operations. This might lead to unauthorized access to sensitive data stored in alternate data streams, potentially exposing confidential information or enabling further system compromise.

Mitigation Strategies

Update the Linux kernel to the latest patched version to resolve the ksmbd ADS I/O credential handling issue.

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