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 648323C5DA6 for ; Mon, 10 Aug 2026 12:02:01 +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=1786363322; cv=none; b=gAF9hx31foLWer3U1LC3atakH6mWLkLvMCX1rZRB7RYifBdX6q0TmSXvwL/SlpMgTiP+0tk8za+Jc6LU02xS097tSu9bft3W06TLdKSnWeGnPAN5pHnGeSrPvrYvKURVrBH8cG8kaJw2+vJNMH8icWShexNnIr5/DhNBf/cKFnw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786363322; c=relaxed/simple; bh=oOO/KVgJJ9HIWEHtVpub50QmfBS0NvSGNIrSk0AQiBM=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=aejdh0hhDgxS8F2GNpN/spnHdbjIhU/1ehcO+A/WaO9MZH/nSDCIWZguadeon3wXOoJLkxz0B1GhBJPRN8Cx8U60ARRTs/dWkrcw8knyUi5S5Uy67NeXagZkVNaeZJt9fsXm3jObiSPJYewoI3NlI4VegYAFkLbqDTuHZFTxXEE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=vnD2JtL1; 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="vnD2JtL1" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A00DD1F000E9; Mon, 10 Aug 2026 12:02:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1786363320; bh=eQWpAuGMwyOflEfSzVuFHUiKgTOl7fGfR/xy3DBxYDc=; h=From:To:Cc:Subject:Date:Reply-To; b=vnD2JtL1fe9KW98feuVDD0MGOCUisNgBTtVNJrM9D+DX0cEzwWfGu7PG3r6I4p0sH 7f/933FeuMCoraHRJHkmtKCOO1gVIza8OzYONjbsc5sqOBDHSwdnldIwqC1FhOh9rZ tFSy2VQu4R0m7y78Q5XHUb2O8+DDvsFTLZj1gnUs= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-68118: tcp: challenge ACK for non-exact RST in SYN-RECEIVED Date: Mon, 10 Aug 2026 13:57:15 +0200 Message-ID: <2026081055-CVE-2026-68118-a409@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=3045; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=iJELasPccixIXB9PnRs+J5YkLp8fTzw9l4ktbY2fOuo=; b=owGbwMvMwCRo6H6F97bub03G02pJDFmVe9qvH1LMfPRDI2a9qPuFXZ5f/rzm0gtfdqfhk0qbV 5v+ZsWMjlgWBkEmBlkxRZYv23iO7q84pOhlaHsaZg4rE8gQBi5OAZgIfwjD/OTwktjeF9Z7tO9+ 9H+rLvV2zutJexkWrDYS2ihus6e7sdv74h2LXQmBT6btBQA= 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: tcp: challenge ACK for non-exact RST in SYN-RECEIVED The SYN-RECEIVED request-socket path in tcp_check_req() accepts an in-window RST without requiring SEG.SEQ to exactly match RCV.NXT. A non-exact RST therefore removes the request instead of eliciting a challenge ACK. RFC 9293 section 3.10.7.4 applies the RFC 5961 reset check in SYN-RECEIVED: an exact RST resets the connection, while a non-exact in-window RST must trigger a challenge ACK and be dropped. Apply that check before the ACK-field validation, following the RFC sequence-number, RST, then ACK processing order. Factor the per-netns challenge ACK quota out of tcp_send_challenge_ack() so request sockets can share it. Use the request socket's send_ack() callback and its own out-of-window ACK timestamp to send and rate-limit the response. The Linux kernel CVE team has assigned CVE-2026-68118 to this issue. Affected and fixed versions =========================== Issue introduced in 3.6 with commit 282f23c6ee343126156dd41218b22ece96d747e3 and fixed in 6.18.42 with commit 234f9ffbd9b2c1b24ec67200ea3cff07401bec48 Issue introduced in 3.6 with commit 282f23c6ee343126156dd41218b22ece96d747e3 and fixed in 7.1.6 with commit 22cec809b048495310f206d9abbcdbbfbdce3ae3 Issue introduced in 3.6 with commit 282f23c6ee343126156dd41218b22ece96d747e3 and fixed in 7.2-rc5 with commit a28c4fcbf774e23b4779cae468e3497a5ad1f4a1 Issue introduced in 3.0.58 with commit 86791bbfe5ed7b275be040cfeff049a1624af1b7 Issue introduced in 3.2.37 with commit 61f69dc4e40e41b0018f00fa4aeb23d3239556fb Issue introduced in 3.4.25 with commit 34fb350281ced2a72707a5c0064f69992d440edb 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-2026-68118 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: include/net/tcp.h net/ipv4/tcp_input.c net/ipv4/tcp_minisocks.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/234f9ffbd9b2c1b24ec67200ea3cff07401bec48 https://git.kernel.org/stable/c/22cec809b048495310f206d9abbcdbbfbdce3ae3 https://git.kernel.org/stable/c/a28c4fcbf774e23b4779cae468e3497a5ad1f4a1