From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4119C3AA4EB for ; Sat, 15 Aug 2026 12:31:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786797072; cv=none; b=TQ5fK2YEz3UN+NqsW6YDWDX8B3F8mq4kWJy37/Qkw1X/+xjwpMKn5dg4ZYYj5wprzgncQZ3vBbn9tNLugH3pLF48rQdkP4BfTCh6POfIE5yeKFq6e8g7wTMI3QILQfm9XmuJFLSIhufxZIJK+00ntYCzCmdLSrbhtNuCFvc36jI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786797072; c=relaxed/simple; bh=c7mOEA2jTiWoTKGJJmFajPI0GaLvA48qXgelBBOdNAc=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=rbdt/H3S2cwre3+8APkNnv2CX7ddY1IGHtEk+2sguE+0rPIxDZ3SeHiA0Npy6ygajuaBzuFVYXs3TyGWhfMIUqIE3OeFQtX7pJYqk6iwLtEU5YYZPvyPHUaHdLYvy3NfxTcksZ2jgilg+Qu/5uR+4lwHmYwd9n8+MVbCsIGp0Ms= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=iPsy6WWk; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="iPsy6WWk" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 98D151F000E9; Sat, 15 Aug 2026 12:31:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1786797071; bh=uE7S/ln/+AiAlwynAum/eW4TKDcCLOxAYD31flZupcE=; h=From:To:Cc:Subject:Date:Reply-To; b=iPsy6WWkmAaYaqE/bMAx7yOOeWn+3pFXYbmIUKDYWOq2JBrQhHpEV5wguVXxmStiP dNORhdl51T+7z1sHPhgxozkLkeqh6CcWT7zGdi5BQ8hKhP01fKhho110LKG7uNI7p8 N3zWC4cPJcc7zpbRhEGEvs8Sk5og9kadLfJ6kejQ= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-74521: ksmbd: use memcmp() to compare ClientGUIDs Date: Sat, 15 Aug 2026 21:26:42 +0900 Message-ID: <2026081544-CVE-2026-74521-7ade@gregkh> X-Mailer: git-send-email 2.55.0 Reply-To: , Precedence: bulk X-Mailing-List: linux-cve-announce@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2078; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=2kyJ5t66N4VNsZHKnPtvk2skfGj0/GlD4byGYGawe+k=; b=owGbwMvMwCRo6H6F97bub03G02pJDFkNUSeuT8w/8HVC8wOPdzf2Tvl4QNoo57DSs90X3MIWT duntCNxT0csC4MgE4OsmCLLl208R/dXHFL0MrQ9DTOHlQlkCAMXpwBMZOkLhtls//kvtVUL8//W vjLRbufZnXfWubYxzGIyLfV4f2+h/Rx1Ja5L/19MezipcCIA X-Developer-Key: i=gregkh@linuxfoundation.org; a=openpgp; fpr=F4B60CC5BF78C2214A313DCB3147D40DDB2DFB29 Content-Transfer-Encoding: 8bit From: Greg Kroah-Hartman Description =========== In the Linux kernel, the following vulnerability has been resolved: ksmbd: use memcmp() to compare ClientGUIDs ClientGUID is a fixed-size binary value and can contain embedded NUL bytes. strncmp() stops comparing at the first NUL byte, so different ClientGUID values can incorrectly be treated as equal. Use memcmp() in SMB3 multichannel session binding and FSCTL_VALIDATE_NEGOTIATE_INFO to compare all SMB2_CLIENT_GUID_SIZE bytes. The Linux kernel CVE team has assigned CVE-2026-74521 to this issue. Affected and fixed versions =========================== Issue introduced in 5.15 with commit e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 and fixed in 7.1.8 with commit d535363299822c5caa543787b21bd5cfa3e41949 Issue introduced in 5.15 with commit e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 and fixed in 7.2-rc6 with commit e8bb506e6ef749ac0336f3e579d8d02396b7d832 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-2026-74521 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/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/d535363299822c5caa543787b21bd5cfa3e41949 https://git.kernel.org/stable/c/e8bb506e6ef749ac0336f3e579d8d02396b7d832