CVE-2026-64388
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: smb/client: fix chown/chgrp with SMB3 POSIX Extensions Ownership (chown) and group (chgrp) modifications were being ignored when mounting with SMB3 POSIX Extensions unless CIFS_MOUNT_CIFS_ACL or CIFS_MOUNT_MODE_FROM_SID were also explicitly set. Fix this by checking for posix_extensions in cifs_setattr_nounix() when updating UID and GID, ensuring that id_mode_to_cifs_acl() is called to map and set the ownership/group information on the server.

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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-2026-64388
EUVD
EUVD-2026-48932

Affected Vendors & Products

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

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel affects the SMB client when using SMB3 POSIX Extensions. It allows ownership and group modifications (chown/chgrp) to be ignored unless specific mount options are set. The fix ensures proper handling of UID and GID changes by checking for posix_extensions and calling id_mode_to_cifs_acl().

Impact Analysis

If you use SMB3 POSIX Extensions for file sharing, this vulnerability could prevent proper ownership and group changes from being applied. This may lead to incorrect file permissions, access issues, or unintended data exposure if permissions are not enforced as expected.

Mitigation Strategies

Update the Linux kernel to the patched version where the fix for SMB3 POSIX Extensions chown/chgrp is included. Ensure mounts using SMB3 POSIX Extensions explicitly set CIFS_MOUNT_CIFS_ACL or CIFS_MOUNT_MODE_FROM_SID to enforce ownership and group modifications.

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