In the Linux kernel, the following vulnerability has been resolved: smb/client: fix chown/chgrp with SMB3 POSIX Extensions Ownership (chown) and… (CVE-2026-64388)
A vulnerability in the Linux kernel's SMB client related to SMB3 POSIX Extensions was resolved. The issue caused ownership (chown) and group (chgrp) changes to be ignored unless specific mount options were set. This was fixed by ensuring proper checks and mapping of ownership and group information when updating UID and GID on the server.
AI Analysis
Technical Summary
The Linux kernel SMB client had a vulnerability where ownership and group modifications via chown and chgrp commands were ignored when mounting with SMB3 POSIX Extensions unless CIFS_MOUNT_CIFS_ACL or CIFS_MOUNT_MODE_FROM_SID mount options were explicitly enabled. The fix involved adding a check for posix_extensions in the cifs_setattr_nounix() function to correctly update UID and GID by calling id_mode_to_cifs_acl(), ensuring ownership and group information is properly set on the SMB server.
Potential Impact
Ownership and group changes on files mounted via SMB3 POSIX Extensions could be silently ignored, potentially leading to incorrect file permissions and access control on SMB shares. This could affect system security by not enforcing intended ownership changes, but no direct exploitation or remote code execution impact is described.
Mitigation Recommendations
A fix has been implemented in the Linux kernel to address this issue. Users should update to the fixed kernel version once available. Patch status is not explicitly confirmed in the provided data; therefore, check the official Linux kernel advisories or vendor updates for the exact fixed versions and apply them accordingly.
In the Linux kernel, the following vulnerability has been resolved: smb/client: fix chown/chgrp with SMB3 POSIX Extensions Ownership (chown) and… (CVE-2026-64388)
Description
A vulnerability in the Linux kernel's SMB client related to SMB3 POSIX Extensions was resolved. The issue caused ownership (chown) and group (chgrp) changes to be ignored unless specific mount options were set. This was fixed by ensuring proper checks and mapping of ownership and group information when updating UID and GID on the server.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The Linux kernel SMB client had a vulnerability where ownership and group modifications via chown and chgrp commands were ignored when mounting with SMB3 POSIX Extensions unless CIFS_MOUNT_CIFS_ACL or CIFS_MOUNT_MODE_FROM_SID mount options were explicitly enabled. The fix involved adding a check for posix_extensions in the cifs_setattr_nounix() function to correctly update UID and GID by calling id_mode_to_cifs_acl(), ensuring ownership and group information is properly set on the SMB server.
Potential Impact
Ownership and group changes on files mounted via SMB3 POSIX Extensions could be silently ignored, potentially leading to incorrect file permissions and access control on SMB shares. This could affect system security by not enforcing intended ownership changes, but no direct exploitation or remote code execution impact is described.
Mitigation Recommendations
A fix has been implemented in the Linux kernel to address this issue. Users should update to the fixed kernel version once available. Patch status is not explicitly confirmed in the provided data; therefore, check the official Linux kernel advisories or vendor updates for the exact fixed versions and apply them accordingly.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-p59x-f8qp-h8m2
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-64388"]
- Ecosystems
- []
- Database Specific Severity
- null
- Cvss Version
- null
Threat ID: 6a65420a9c2644c7f8084480
Added to database: 07/25/2026, 23:08:58 UTC
Last enriched: 07/25/2026, 23:28:08 UTC
Last updated: 07/26/2026, 05:12:14 UTC
Views: 6
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