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 3208D37C0FF for ; Sat, 15 Aug 2026 06:29:20 +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=1786775361; cv=none; b=bUruP3lFIo2+vE7/UGToTJ9w7gwq5KbX6NUzaXX13wjnA5bHh6LEyvVh5gsJJaR/HefQQWU8W+Ddrf8NRdfiWVx/lxAI9TY0Q89P/rJaZeoOi093Ew0ieV9qV53wvGPGW66sIirDj4wJMLqQ/wW+oHalIqq91wFwy3eLS6jnfm4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786775361; c=relaxed/simple; bh=Ly7EInEjSgvJ4fM8Z/walJl+1GMtQAQbt3CELSmBgbo=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=fmYypEzxPUp69uROe1n/213MYIxKekLeGGvzNWGXHSu0VhYpA3UXKnzMRa8xiLFunYSGuJbyNsHU7WBJBb6xOzn8Bw59FPKsqGwWPYDPWJsgfEX0NVIVfRd2NfPID1gdLN1f7cORhmIpBzJhMgsUZ53X1FdiQ8FsYFwPt8HHkDY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=R4+vtZAB; 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="R4+vtZAB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7B69E1F000E9; Sat, 15 Aug 2026 06:29:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1786775360; bh=enAJdKaiwzvw1UiIWfJYUpDsQHNmunpR5rXF1pRJTfA=; h=From:To:Cc:Subject:Date:Reply-To; b=R4+vtZABYqkM3fjaOepTV9PTG19su8NfR6/PgU/u/MWuS1JNj8ON6H2vK7my/FIsK POK+LnVgD+lwvCpb9wMacKBe4BEl9RTBjf4un97UVqd5DFDzb5YSIfbRuNCld5pKS2 QoufK2bHoPtBFxoC8b9VCDE6JaGGs2iEtoJnHi6w= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-72421: ipv4: fib: Don't ignore error route in local/main tables. Date: Sat, 15 Aug 2026 15:08:20 +0900 Message-ID: <2026081525-CVE-2026-72421-d299@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=3883; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=YFxoU/dNzBCL7X9OAbm+48REiBaE+KmnxuWsSaL/fnE=; b=owGbwMvMwCRo6H6F97bub03G02pJDFkNDB+Dtktk1Rxl+uhxwy1I9rGVY1W7xredQTtuTDS8I qD5MvJqRywLgyATg6yYIsuXbTxH91ccUvQytD0NM4eVCWQIAxenAEyE05NhwaxlcZcLC/sckqLO GFn+anTJ+5w1gWE2C8/xs67G979n512wjf+i9+o204s+AA== 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: ipv4: fib: Don't ignore error route in local/main tables. When CONFIG_IP_MULTIPLE_TABLES is enabled but no rule is added, fib_lookup() performs route lookup directly on two tables. Since the first lookup does not properly bail out, the result of an error route in the merged local/main table could be overwritten by another route in the default table: # unshare -n # ip link set lo up # ip route add 192.168.0.0/24 dev lo table 253 # ip route add unreachable 192.168.0.0/24 # ip route get 192.168.0.1 192.168.0.1 dev lo table default uid 0 cache Once a random rule is added, the error route is respected: # ip rule add table 0 # ip rule del table 0 # ip route get 192.168.0.1 RTNETLINK answers: No route to host Let's fix the inconsistent behaviour. The Linux kernel CVE team has assigned CVE-2026-72421 to this issue. Affected and fixed versions =========================== Issue introduced in 3.6 with commit f4530fa574df4d833506c53697ed1daa0d390bf4 and fixed in 5.10.261 with commit a29e95fbc51e8a1b932773fd0e259b2080881443 Issue introduced in 3.6 with commit f4530fa574df4d833506c53697ed1daa0d390bf4 and fixed in 5.15.212 with commit 5ae18d87a45698e8244d0fcba64c658c35a7dd3d Issue introduced in 3.6 with commit f4530fa574df4d833506c53697ed1daa0d390bf4 and fixed in 6.1.178 with commit 9127589aabdee588278e8d0d0bd3709a760a92c8 Issue introduced in 3.6 with commit f4530fa574df4d833506c53697ed1daa0d390bf4 and fixed in 6.6.145 with commit 49eaf1403201357762d745a35882fb734107d763 Issue introduced in 3.6 with commit f4530fa574df4d833506c53697ed1daa0d390bf4 and fixed in 6.12.97 with commit fd25996f57a95d56bc568c89b4921edcf334b7d8 Issue introduced in 3.6 with commit f4530fa574df4d833506c53697ed1daa0d390bf4 and fixed in 6.18.40 with commit 828fad4fd418bcdb9f5d66fec0d184c52a85ec31 Issue introduced in 3.6 with commit f4530fa574df4d833506c53697ed1daa0d390bf4 and fixed in 7.1.5 with commit a668fa160247d7bbe921548cb845f607b8b9305f Issue introduced in 3.6 with commit f4530fa574df4d833506c53697ed1daa0d390bf4 and fixed in 7.2-rc1 with commit b72f0db64205d9ce462038ba995d5d31eff32dc1 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-2026-72421 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/ip_fib.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/a29e95fbc51e8a1b932773fd0e259b2080881443 https://git.kernel.org/stable/c/5ae18d87a45698e8244d0fcba64c658c35a7dd3d https://git.kernel.org/stable/c/9127589aabdee588278e8d0d0bd3709a760a92c8 https://git.kernel.org/stable/c/49eaf1403201357762d745a35882fb734107d763 https://git.kernel.org/stable/c/fd25996f57a95d56bc568c89b4921edcf334b7d8 https://git.kernel.org/stable/c/828fad4fd418bcdb9f5d66fec0d184c52a85ec31 https://git.kernel.org/stable/c/a668fa160247d7bbe921548cb845f607b8b9305f https://git.kernel.org/stable/c/b72f0db64205d9ce462038ba995d5d31eff32dc1