From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 0ACEE3E5EFF for ; Fri, 8 May 2026 13:42:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778247728; cv=none; b=l31/IUudFCnIkfA2K0ivz3m/Vh7HHPOnTbtYCWnE0PXW/XXuEavbkJlWL+MncBbxGyw6nKKuP0c4TTCDrwUr9lCQglw3z3LN3x2FAhnK3QZLxOXtTjYoPyM5bFg/2Dla4ejyTFThOkOsN+otP7TckTkQ5+MqXSnkQ/+SdCCPa+o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778247728; c=relaxed/simple; bh=GB3xUG1cqPVT6RXmAHn4MIEzn0ytqat9sTv2tJN9ad4=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=ETTkX4kp1Zj7IFiS4RBYq9bUwNW04znwgJa96K4AEObrWKhvOWsUqHcLQvUuuV86d6XImLHsIsw4BIZhp/1YaL0Ck5CTHk+DCu8ytEmweFX/ueAZZt+qmbryu47QvGuOTo/4JZ0V09MUDu4W+XWDy7qMKSJOgImmXmD3P2Hg98c= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=vsc59MKn; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="vsc59MKn" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 50FE1C2BCB0; Fri, 8 May 2026 13:42:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1778247727; bh=GB3xUG1cqPVT6RXmAHn4MIEzn0ytqat9sTv2tJN9ad4=; h=From:To:Cc:Subject:Date:Reply-To:From; b=vsc59MKnjzTi7ldxs7DvXXMiiC3Cdea8IsiJynfO412714JsqtSjwW+PgbJQ8ssaj n5nmOaLUh8J0d2pruPraanClFIsXRTMTs6euJaFZE1bYf67Uk1lAjyzfntvSVkVI+H qfJbAJkiatu2pEyWHW5N/s6mgCUNnUG5OeySaD/Y= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-43350: smb: client: require a full NFS mode SID before reading mode bits Date: Fri, 8 May 2026 15:41:58 +0200 Message-ID: <2026050856-CVE-2026-43350-2b94@gregkh> X-Mailer: git-send-email 2.54.0 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=3093; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=TXRvHeeMmz5DEviPJo2WAkCzaghnWRwDss6d7aLnuR4=; b=owGbwMvMwCRo6H6F97bub03G02pJDJl/X6gEspd5HhM9msutLPku9nBeweePFjd21f/qqVl0K p8hXOVSRywLgyATg6yYIsuXbTxH91ccUvQytD0NM4eVCWQIAxenAExkiT7Dgsb7Z5iCTE+r+so5 xSpF7F5dYWqykGFBV8nrq306YWbSbhtjF0/vv+YplbIcAA== 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: smb: client: require a full NFS mode SID before reading mode bits parse_dacl() treats an ACE SID matching sid_unix_NFS_mode as an NFS mode SID and reads sid.sub_auth[2] to recover the mode bits. That assumes the ACE carries three subauthorities, but compare_sids() only compares min(a, b) subauthorities. A malicious server can return an ACE with num_subauth = 2 and sub_auth[] = {88, 3}, which still matches sid_unix_NFS_mode and then drives the sub_auth[2] read four bytes past the end of the ACE. Require num_subauth >= 3 before treating the ACE as an NFS mode SID. This keeps the fix local to the special-SID mode path without changing compare_sids() semantics for the rest of cifsacl. The Linux kernel CVE team has assigned CVE-2026-43350 to this issue. Affected and fixed versions =========================== Issue introduced in 5.4 with commit e2f8fbfb8d09c06decde162090fac3ee220aa280 and fixed in 6.6.136 with commit b53b8e98c23310294fc45fc686db5ee860311896 Issue introduced in 5.4 with commit e2f8fbfb8d09c06decde162090fac3ee220aa280 and fixed in 6.12.84 with commit c8eef12af1cc73031639ea7cf16e0b10e2536b0b Issue introduced in 5.4 with commit e2f8fbfb8d09c06decde162090fac3ee220aa280 and fixed in 6.18.25 with commit 38a69f08ee82c450d3e4168707fff2e317dc3ff7 Issue introduced in 5.4 with commit e2f8fbfb8d09c06decde162090fac3ee220aa280 and fixed in 7.0.2 with commit f8488c07bea2431ee12a6067d736578064fa46b4 Issue introduced in 5.4 with commit e2f8fbfb8d09c06decde162090fac3ee220aa280 and fixed in 7.1-rc1 with commit 2757ad3e4b6f9e0fed4c7739594e702abc5cab21 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-2026-43350 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/client/cifsacl.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/b53b8e98c23310294fc45fc686db5ee860311896 https://git.kernel.org/stable/c/c8eef12af1cc73031639ea7cf16e0b10e2536b0b https://git.kernel.org/stable/c/38a69f08ee82c450d3e4168707fff2e317dc3ff7 https://git.kernel.org/stable/c/f8488c07bea2431ee12a6067d736578064fa46b4 https://git.kernel.org/stable/c/2757ad3e4b6f9e0fed4c7739594e702abc5cab21