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 7A4D039A7E1 for ; Sun, 19 Jul 2026 14:18:52 +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=1784470737; cv=none; b=LnJCNP7KA/qkVYed3dUVcPASHLbiimWuz9Esje6wKIV7CFFrE/Vcw30pMCmwStQdst2kY+433/GVhUFLve/7X4VmbLYR+rDq9s0EhmZUguNGhR0pl6oZCrm9PY5tLQVLh0WYNowUN93WnzkmzGjI8uv5wZs1kVc6CwVS3+xcBjI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784470737; c=relaxed/simple; bh=BOfK7E6dKq5ISQkCnEorfwawH8lNYJCgY4yFGE3s24E=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=FgRTmlAxjTmnuYW5vA2cvlgMeHD4w8Va44GHkjWmpmhx6+x15o7Dm7Tq8RFFb8gmf24dAYpFibaRCWGyUbz2lBTRjmz6OKbnNN0G/cmPhmHUiTiANDVCJzEGlKuPzXsdnuIPu7e6m4rorf/8AFrDxsPj9HkG5Rqh1BXRzdw3Z1Y= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Vp4dR0Tw; 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="Vp4dR0Tw" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7A02F1F00A3A; Sun, 19 Jul 2026 14:18:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784470728; bh=+6Y8N+nCRYpFENMqPrxWBHhzN7kTVsX9/yVC/iXbOVI=; h=From:To:Cc:Subject:Date:Reply-To; b=Vp4dR0TwUvcWoAQasYOAjfWXHEmU0VtHtccJT9RA9DNCszw8mRUgr4YyP5XU6IFVb LYibwSr1kxos87mGm0fJ7PJ0pInma9eanGAoC7ZHP9VwUNcTA0MtaPymXkiKXbxgF9 ufo0K/vmA1DN2N5wSCo2zYOkQIfaHrnRi7g88wuA= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-63867: mptcp: close TOCTOU race while computing rcv_wnd Date: Sun, 19 Jul 2026 16:17:12 +0200 Message-ID: <2026071912-CVE-2026-63867-eac1@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=3291; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=DbQy0A6zTIReUUmcoobL28YDg4A4cCcd41ql9r+7s8I=; b=owGbwMvMwCRo6H6F97bub03G02pJDFkxdzIOCgj3bLq3+dYC9+JQjT8e+/j9j//5KMc0SdFl1 aObIu7VHbEsDIJMDLJiiixftvEc3V9xSNHL0PY0zBxWJpAhDFycAjCR1RMZ5hd73pXqXfSrPHYz 66opW2vP6AovlGaYZ9D7vdp0sfGJ3oZD5t/e35fh/ZsuAAA= 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: mptcp: close TOCTOU race while computing rcv_wnd The MPTCP output path access locklessly the MPTCP-level ack_seq in multiple times, using possibly different values for the data_ack in the DSS option and to compute the announced rcv wnd for the same packet. Refactor the cote to avoid inconsistencies which may confuse the peer. Also ensure that the MPTCP level rcv wnd is updated only when the egress packet actually contains a DSS ack. The Linux kernel CVE team has assigned CVE-2026-63867 to this issue. Affected and fixed versions =========================== Issue introduced in 5.11 with commit fa3fe2b150316b294f2c662653501273ff25bba8 and fixed in 5.15.210 with commit 301a33fd590c408a05c5df800e0cc1e6a8a2f8f8 Issue introduced in 5.11 with commit fa3fe2b150316b294f2c662653501273ff25bba8 and fixed in 6.1.176 with commit 68364963e5baf03f16b4420292291f75c8f66497 Issue introduced in 5.11 with commit fa3fe2b150316b294f2c662653501273ff25bba8 and fixed in 6.6.143 with commit 907ac6b1658e0277f979fcdfae2a753b495c1510 Issue introduced in 5.11 with commit fa3fe2b150316b294f2c662653501273ff25bba8 and fixed in 6.12.94 with commit c4f4cf60797974873dbc8e100144682a6f2f861f Issue introduced in 5.11 with commit fa3fe2b150316b294f2c662653501273ff25bba8 and fixed in 6.18.36 with commit 3b8cbba7c0ed31189c89f90be247b8973ffa79ef Issue introduced in 5.11 with commit fa3fe2b150316b294f2c662653501273ff25bba8 and fixed in 7.0.13 with commit 8f4f0a157e8436a05bf8c3670b24dbc258911c43 Issue introduced in 5.11 with commit fa3fe2b150316b294f2c662653501273ff25bba8 and fixed in 7.1 with commit 8ab24fdebc369c0dfb90f82c1650b1e66662bb45 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-2026-63867 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: net/mptcp/options.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/301a33fd590c408a05c5df800e0cc1e6a8a2f8f8 https://git.kernel.org/stable/c/68364963e5baf03f16b4420292291f75c8f66497 https://git.kernel.org/stable/c/907ac6b1658e0277f979fcdfae2a753b495c1510 https://git.kernel.org/stable/c/c4f4cf60797974873dbc8e100144682a6f2f861f https://git.kernel.org/stable/c/3b8cbba7c0ed31189c89f90be247b8973ffa79ef https://git.kernel.org/stable/c/8f4f0a157e8436a05bf8c3670b24dbc258911c43 https://git.kernel.org/stable/c/8ab24fdebc369c0dfb90f82c1650b1e66662bb45