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CVE-2026-64388

7.8 · HIGH

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 whe…

Published Jul 25, 2026EPSS 0.13%

Overview

CVE-2026-64388 is a high-severity vulnerability. It was published on July 25, 2026 and has a CVSS 3.1 base score of 7.8 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.8, rated HIGH. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refgit.kernel.org/stable/c/550cfb8a81181331d4d0f76ab75ee58a0bf41e3eRefgit.kernel.org/stable/c/760ef2c579c2609cf17fb1cd5392f64d42d43d33

How CyberStrike helps

Frequently asked questions

What is CVE-2026-64388?

CVE-2026-64388 is a high-severity vulnerability. It was published on July 25, 2026 and has a CVSS 3.1 base score of 7.8 (HIGH).

How severe is CVE-2026-64388?

This vulnerability has a CVSS 3.1 base score of 7.8, rated HIGH. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2026-64388?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-64388?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-64388 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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