linux-cve-announce - CVE-2025-71150: ksmbd: Fix refcount leak when invalid session is found on session lookup

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Message-ID: <2026012328-CVE-2025-71150-1b7c@gregkh>
Date: Fri, 23 Jan 2026 15:15:30 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-71150: ksmbd: Fix refcount leak when invalid session is found on session lookup

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

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

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

ksmbd: Fix refcount leak when invalid session is found on session lookup

When a session is found but its state is not SMB2_SESSION_VALID, It
indicates that no valid session was found, but it is missing to decrement
the reference count acquired by the session lookup, which results in
a reference count leak. This patch fixes the issue by explicitly calling
ksmbd_user_session_put to release the reference to the session.

The Linux kernel CVE team has assigned CVE-2025-71150 to this issue.


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

	Fixed in 6.1.160 with commit 0fb87b28cafae71e9c8248432cc3a6a1fd759efc
	Fixed in 6.6.120 with commit e54fb2a4772545701766cba08aab20de5eace8cd
	Fixed in 6.12.64 with commit 02e06785e85b4bd86ef3d23b7c8d87acc76773d5
	Fixed in 6.18.3 with commit 8cabcb4dd3dc85dd83a37d26efcc59a66a4074d7
	Fixed in 6.19-rc2 with commit cafb57f7bdd57abba87725eb4e82bbdca4959644

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-2025-71150
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


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/0fb87b28cafae71e9c8248432cc3a6a1fd759efc
	https://git.kernel.org/stable/c/e54fb2a4772545701766cba08aab20de5eace8cd
	https://git.kernel.org/stable/c/02e06785e85b4bd86ef3d23b7c8d87acc76773d5
	https://git.kernel.org/stable/c/8cabcb4dd3dc85dd83a37d26efcc59a66a4074d7
	https://git.kernel.org/stable/c/cafb57f7bdd57abba87725eb4e82bbdca4959644