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 01B3C58B6BB for ; Fri, 11 Sep 2026 20:01:29 +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=1789156896; cv=none; b=SJox6sVBsJNX1ofIQ771OULkFhEFPxJgB2g9ZtqC7KYkHKx+/YwrukLRs11bfqOW0e+QeCxTm8VgqgPFbAcd2VrwFb8ZWniLO73Dfr5vhCW7XP6FzG64h45OxvnBeKEHiIpZ7nbA7IFv/mqZ+jcr6ZEjKqJvXWm9aOM/1FHtuCg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789156896; c=relaxed/simple; bh=XBzdjOC4mGup9+8UbXnOBGAQF67LOXBW+9Kjtaa4z+4=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=Pm/tQV3NLzykuTbZor8GnS5n8ZM91pkXXyOP2oSwIhdS2LrbTQyVfMb6RCWxt6USoxClukIq3RKRnyOInckADo5sLuO+P/t2G2GHp1mXis4zFGytIrf2m3A9O7b80REhUK2dH8fPvstpNtT3xxxiADEsek5vNjQkQnM6476xhSU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=QW8eaziG; 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="QW8eaziG" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2B9181F00899; Fri, 11 Sep 2026 20:01:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789156889; bh=sIKUu0yQT1QYw5ga8jANRtCgRXoDrGx1fKx/GxnBCJU=; h=From:To:Cc:Subject:Date:Reply-To; b=QW8eaziGNs/U0dcbFknksSlyTLuoimxndft3neP6mdkCFlscy1IZdSpLJIw9GNVBx hiikZQAspxosnO+Tj93zI0BWJoxaBeGABiwLDmkrD59WBHtvnOMWsV4B2lXCU+UjAU 5HiIi4+x5zZORbBZGFh4YtyX8J9StzCPIjMNpedU= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-89631: smb: client: reject a tree connect response whose byte count is too small Date: Fri, 11 Sep 2026 21:45:20 +0200 Message-ID: <2026091139-CVE-2026-89631-d03e@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=2778; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=PNsaGIJoOEB8GtqHrQxNUFjheNMD5Krkd7Za451lvoI=; b=owGbwMvMwCRo6H6F97bub03G02pJDFlLIovNl9q2mm6M+ZJWzD7j8axZv60mNH1eeDfEULP5b 8O3K8xXO2JZGASZGGTFFFm+bOM5ur/ikKKXoe1pmDmsTCBDGLg4BWAiD74xzA8snlQ+f4p9W/vL RY8Ke2b/7f8ZsoFhwQ6xBRd22+8/7PZwgQqD1I+t7LkXFgIA 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: reject a tree connect response whose byte count is too small CIFSTCon() bounds its strnlen() over the byte area with the server's ByteCount minus two, which for ByteCount 0 or 1 goes negative as an int and converts to a huge size_t. The later subtraction wraps the __u16 bytes_left, and that is what bounds cifs_strndup_from_utf16(): a bound of up to 65535 against a ~16 KB cifs_req_poolp object runs off the end of the slab object, and the bytes reach userspace through tcon->nativeFileSystem in /proc/fs/cifs/DebugData. Reject a byte area too small for what the parser consumes. Two bytes is the least it can consume, and no conformant response carries fewer. The new trace point is the 129th smb_eio_trace entry, which __mode(byte) cannot represent, so the attribute goes with it. The Linux kernel CVE team has assigned CVE-2026-89631 to this issue. Affected and fixed versions =========================== Issue introduced in 2.6.30 with commit cc20c031bb067eb3280a1c4b5c42295093e24863 and fixed in 6.18.51 with commit 3be89e8039a85fa3b6cd5f9dcc4c1459eb356c2d Issue introduced in 2.6.30 with commit cc20c031bb067eb3280a1c4b5c42295093e24863 and fixed in 7.2.4 with commit 411e484fe71a7f1028de617447edad9cb6d9d68a Issue introduced in 2.6.30 with commit cc20c031bb067eb3280a1c4b5c42295093e24863 and fixed in 7.3-rc1 with commit 65deb18359341141d37dc86fc7853511be3c87a7 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-2026-89631 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/cifssmb.c fs/smb/client/trace.h 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/3be89e8039a85fa3b6cd5f9dcc4c1459eb356c2d https://git.kernel.org/stable/c/411e484fe71a7f1028de617447edad9cb6d9d68a https://git.kernel.org/stable/c/65deb18359341141d37dc86fc7853511be3c87a7