CVE-2026-64138: ksmbd: validate SID in parent security descriptor during ACL inheritance

CVE-2026-64138: ksmbd: validate SID in parent security descriptor during ACL inheritance

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

ksmbd: validate SID in parent security descriptor during ACL inheritance

Introduce smb_validate_ntsd_sid() helper to safely validate Owner SID
and Group SID inside the NT Security Descriptor (smb_ntsd) retrieved
from the parent directory.

The Linux kernel CVE team has assigned CVE-2026-64138 to this issue.


Affected and fixed versions
===========================

	Fixed in 6.12.92 with commit f0e5c9c663badc9982e6941322eef1cb17de0f11
	Fixed in 6.18.34 with commit 18d8db24b0a5b7be4829238dd4022236df02d421
	Fixed in 7.0.11 with commit 1c9d0646a9959752f11ca1080dc1ff26bd1756cb
	Fixed in 7.1 with commit 69f030cf95488ae1186c72ac8c66fd279664ea7f

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-64138
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	fs/smb/server/smbacl.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/f0e5c9c663badc9982e6941322eef1cb17de0f11
	https://git.kernel.org/stable/c/18d8db24b0a5b7be4829238dd4022236df02d421
	https://git.kernel.org/stable/c/1c9d0646a9959752f11ca1080dc1ff26bd1756cb
	https://git.kernel.org/stable/c/69f030cf95488ae1186c72ac8c66fd279664ea7f