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 7010133F5A5 for ; Sat, 22 Aug 2026 15:33:48 +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=1787412829; cv=none; b=CjevZUSd6OlFJP95QfSQQ43m0YoCxnSyUdJX0eILJZW3JckEJ1jaKAnLef/dti2Ekhke+MyzqQ+qg8zfevwBGMQ7IIMc2NguKbdz06PHsITOnOADZw8+z2Pv52Bglx7KHsCIA3CbaJ+CUjEstD1zEVZ75rVKySptfM++MNe+d6c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787412829; c=relaxed/simple; bh=rigV9YJsbS2pQICAbcugsOzFN14kfR342CerY4Dc+BA=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=NbtU42eoI5NXZZQcyxxXfRQVay4myJvxU4tNO86KmaCzmIvGrnFNfgUqB+rKXwu42gQdqSfGayrSP6dyNvsAVGW50YAzYIe/00C1v8DlfFr/CH1R0DzjFny6bD+FHV1UOQKTmuLtIONNTyrnfuH2RvX24AMbIlwR76nbuP1zCEY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=FlywfsyB; 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="FlywfsyB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7A0B11F000E9; Sat, 22 Aug 2026 15:33:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1787412828; bh=FbO0O7e2JZEPB6wGvkTJKAD6kBN0DD8vWNpARYx35IQ=; h=From:To:Cc:Subject:Date:Reply-To; b=FlywfsyBB28UmKpJMl+at5PohcVB53kB/+4eFcp7fGPfB7J32j88nZsz1gQxN0nPs cvPFaN0qeTYk4ktrT90YUHSfxgJMD5J6q7K74TGWv2pRUUln1Fhe6sAr0Ih2T3st4D AvFYgcmDaoFd8K70EPJiM5wHNAriaSEIvawqm/QQ= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-74598: ipv6: fix Route Information option length validation Date: Sat, 22 Aug 2026 17:31:22 +0200 Message-ID: <2026082214-CVE-2026-74598-d1ac@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=4455; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=/Hiq6kNVAls6SSZiWTAmgO5Y6EQsVNqGoIMAovUZ+zk=; b=owGbwMvMwCRo6H6F97bub03G02pJDFmdBw7tKdkvWnQue7bJ7y//74ffKKuJncMlnFEz5aink 59HccjtjlgWBkEmBlkxRZYv23iO7q84pOhlaHsaZg4rE8gQBi5OAZjIrmqGuWKnlUSKFsS2vZfJ 27LqlViK2/o+DoYFG9S3ftJTljL1l3t/TZtzWobIZ9F0AA== 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: ipv6: fix Route Information option length validation rt6_route_rcv() validates the Route Information option (RFC 4191) length against the prefix length, but both checks are off by one. rinfo->length is the ND option length in units of 8 octets and it *includes* the 8-byte option header, so an option carrying N bytes of prefix has length == 1 + N/8. RFC 4191 section 2.3 requires length 3 when Prefix Length is greater than 64, and 2 or 3 when it is greater than 0. The code accepts length >= 2 and length >= 1 respectively. ipv6_addr_prefix() then copies prefix_len/8 bytes out of rinfo->prefix, so a Router Advertisement with (prefix_len=128, length=2) or (prefix_len=64, length=1) makes the kernel read up to 8 bytes past the end of the option. Those bytes end up in the prefix of the route that gets installed, so they are visible to userspace: # RA with a Route Information option (prefix_len=128, length=2) # followed by a source link-layer address option, 01 01 de ad be ef ca fe $ ip -6 route show 2001:db8:dead:beef:101:dead:beef:cafe via fe80::1234 dev veth0 proto ra ^^^^^^^^^^^^^^^^^^ the next option, read out of bounds When the Route Information option is the last one in the packet, those eight bytes come from the skb tail room instead. Reject the option lengths RFC 4191 does not allow. The Linux kernel CVE team has assigned CVE-2026-74598 to this issue. Affected and fixed versions =========================== Issue introduced in 2.6.17 with commit 70ceb4f53929f73746be72f73707cd9f8753e2fc and fixed in 5.10.265 with commit 2f6f94eda12430fb41b24b44a71e2ea4e93561d7 Issue introduced in 2.6.17 with commit 70ceb4f53929f73746be72f73707cd9f8753e2fc and fixed in 5.15.216 with commit 7eac87396c44a312be457ef41d4c5687883be9a2 Issue introduced in 2.6.17 with commit 70ceb4f53929f73746be72f73707cd9f8753e2fc and fixed in 6.1.183 with commit 7309529f257ae18e72112ef9f614edfd6df229bb Issue introduced in 2.6.17 with commit 70ceb4f53929f73746be72f73707cd9f8753e2fc and fixed in 6.6.152 with commit 0b9e02f3bd31c888f2ccdc0ca08e546d6abe9c4d Issue introduced in 2.6.17 with commit 70ceb4f53929f73746be72f73707cd9f8753e2fc and fixed in 6.12.104 with commit ff3cb05289b8a4ef95fa7ea14c7d34818359edbb Issue introduced in 2.6.17 with commit 70ceb4f53929f73746be72f73707cd9f8753e2fc and fixed in 6.18.45 with commit 3b2231e358d26e3aec5d8040b1fb777af03c5f05 Issue introduced in 2.6.17 with commit 70ceb4f53929f73746be72f73707cd9f8753e2fc and fixed in 7.1.9 with commit da64ed1f346ba84df574d6469fa2e422b2511719 Issue introduced in 2.6.17 with commit 70ceb4f53929f73746be72f73707cd9f8753e2fc and fixed in 7.2 with commit d1ad8fb2ac6a1afb71dc22d9ae8efb4dda96c824 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-2026-74598 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/ipv6/route.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/2f6f94eda12430fb41b24b44a71e2ea4e93561d7 https://git.kernel.org/stable/c/7eac87396c44a312be457ef41d4c5687883be9a2 https://git.kernel.org/stable/c/7309529f257ae18e72112ef9f614edfd6df229bb https://git.kernel.org/stable/c/0b9e02f3bd31c888f2ccdc0ca08e546d6abe9c4d https://git.kernel.org/stable/c/ff3cb05289b8a4ef95fa7ea14c7d34818359edbb https://git.kernel.org/stable/c/3b2231e358d26e3aec5d8040b1fb777af03c5f05 https://git.kernel.org/stable/c/da64ed1f346ba84df574d6469fa2e422b2511719 https://git.kernel.org/stable/c/d1ad8fb2ac6a1afb71dc22d9ae8efb4dda96c824