linux-cve-announce - CVE-2026-23226: ksmbd: add chann_lock to protect ksmbd_chann

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Message-ID: <2026021807-CVE-2026-23226-438c@gregkh>
Date: Wed, 18 Feb 2026 15:54:15 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2026-23226: ksmbd: add chann_lock to protect ksmbd_chann_list xarray

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

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

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

ksmbd: add chann_lock to protect ksmbd_chann_list xarray

ksmbd_chann_list xarray lacks synchronization, allowing use-after-free in
multi-channel sessions (between lookup_chann_list() and ksmbd_chann_del).

Adds rw_semaphore chann_lock to struct ksmbd_session and protects
all xa_load/xa_store/xa_erase accesses.

The Linux kernel CVE team has assigned CVE-2026-23226 to this issue.


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

	Fixed in 6.18.11 with commit e4a8a96a93d08570e0405cfd989a8a07e5b6ff33
	Fixed in 6.19.1 with commit 36ef605c0395b94b826a8c8d6f2697071173de6e

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-2026-23226
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/mgmt/user_session.c
	fs/smb/server/mgmt/user_session.h
	fs/smb/server/smb2pdu.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/e4a8a96a93d08570e0405cfd989a8a07e5b6ff33
	https://git.kernel.org/stable/c/36ef605c0395b94b826a8c8d6f2697071173de6e
	https://git.kernel.org/stable/c/4f3a06cc57976cafa8c6f716646be6c79a99e485