Improper access control in Linux kernel - CVE-2026-64395
Published: July 27, 2026
Vulnerability identifier: #VU139582
CSH Severity: Medium
CVSS v4: 7.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-64395
CWE-ID: CWE-284
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to disclose sensitive information.
The vulnerability exists due to improper access control in FSCTL_DUPLICATE_EXTENTS_TO_FILE handling in ksmbd when processing duplicate extents requests. A remote user can use a source handle opened without read access to copy file contents into an attacker-readable destination to disclose sensitive information.
The issue affects the source file access check before invoking file range clone or copy operations.
Affected software
Linux kernel
How to mitigate CVE-2026-64395
Install security update from vendor's repository.
Linux kernel - update to 7.0 rc3
External References
- https://git.kernel.org/stable/c/2d2ab6983620c2d60ce7db72133984ca3873b929
- https://git.kernel.org/stable/c/67bdad9cf01b25030e3bf00bbce6c309319d6663
- https://git.kernel.org/stable/c/a10942af27832c2761d020863a46e79bebe0567d
- https://git.kernel.org/stable/c/b0d4d5cb846a1ddb7aaab9adfb5986e4540e6e5f
- https://git.kernel.org/stable/c/cedff600f1642aa982178503552f0d007bc829c8
- https://git.kernel.org/stable/c/db231af842868268839f9f9619c68cb27830d8be