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 B845F3921DB for ; Sun, 19 Jul 2026 12:04:15 +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=1784462656; cv=none; b=dNw72czMI14d3gbnUzEzrlwcNYc9b3NSTkMzaiUTLu5lpL3NBvcapf0Sq9Bg1JheXISU8Z7PM2EmuqIL+xBDjWaQcgQmaCvTw+Pi7j1H1YOHA9k0Ptx+pfps6tNvTn2PZEi48muuWME3DMJOM0OBaS5FOnrNoGPZLl67LRGvRjg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784462656; c=relaxed/simple; bh=+6UvQfb9qSrj1xSNhnGCVtJFMdfEwzw00zVlhFIDEyQ=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=KwicRId1Cd3Yf/EBA8zEXNdpZFU646lPa4tKuepWeGepvjE6dgHdovTa8JKO9JntHI+zRwGJ7rIR4i9rZOo2K+G2HTUPAVCwMW7gc7nlAHVH0wBVmKY1nsPQj6bDfFFCTsg382nEcJczY27Y78OwQXoCL8AZBfqc3Fb3mz1VTkw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Ajw1pCbN; 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="Ajw1pCbN" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2A3FE1F000E9; Sun, 19 Jul 2026 12:04:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784462655; bh=0oiVX9HWvlOIkWqBAjpO+CZEclmQOugkz4Ybg9GPdTo=; h=From:To:Cc:Subject:Date:Reply-To; b=Ajw1pCbN6Hpf7/rtX7PJwjCkG88oXOaQHSrmubwd13+5vi31F8lEFfeHtrq9R7o1z M9nDh5w0/snRYOmR8gjHhZVqrFZWrhSY2bYKC6wNqW2N2+AbuAnRvD8xMt1JycEW8j 96ovqHoV7K6CF2uG026kAwFDZw4sxkrB92357j4E= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-63829: net: ip_gre: require CAP_NET_ADMIN in the device netns for changelink Date: Sun, 19 Jul 2026 14:02:46 +0200 Message-ID: <2026071908-CVE-2026-63829-ff2a@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=3331; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=HuK6F1vWjECFg26vMTnMtnc4eCJkvAnkk6o4BjStRjo=; b=owGbwMvMwCRo6H6F97bub03G02pJDFkxew7Ex2v8mr9uQ/SGDWXqk5RXROqkaJ/Y+vfHD91Fh osPKqcwd8SyMAgyMciKKbJ82cZzdH/FIUUvQ9vTMHNYmUCGMHBxCsBEpgoxzOGVzJTdnap7zvBR cK296IvyNyUVGxnmcKUdrq1wnmVrXuTj7y29clZg45lNAA== 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: net: ip_gre: require CAP_NET_ADMIN in the device netns for changelink A tunnel changelink() operates on at most two netns, dev_net(dev) and the tunnel link netns t->net. They differ once the device is created in or moved to a netns other than the one the request runs in. The rtnl changelink path checks CAP_NET_ADMIN only against dev_net(dev), so a caller privileged there but not in t->net can rewrite a tunnel that lives in t->net. Add rtnl_dev_link_net_capable() next to rtnl_get_net_ns_capable() in net/core/rtnetlink.c. It requires CAP_NET_ADMIN in the link netns and is skipped when the link netns is dev_net(dev), where the rtnl path already checked it. The other patches in this series use the same helper. Gate ipgre_changelink() and erspan_changelink() with it, at the top of the op before any attribute is parsed, because the parsers update live tunnel fields first. ipgre_netlink_parms() sets t->collect_md before ip_tunnel_changelink() runs. Commit 8b484efd5cb4 ("ip6: vti: Use ip6_tnl.net in vti6_siocdevprivate().") added the same check on the ioctl path. This adds it on RTM_NEWLINK. The Linux kernel CVE team has assigned CVE-2026-63829 to this issue. Affected and fixed versions =========================== Issue introduced in 3.16 with commit b57708add31494175be741ed3fd24023b50c3423 and fixed in 6.12.95 with commit 9831bc9ecb402957810c2045c663fbfe9b09e296 Issue introduced in 3.16 with commit b57708add31494175be741ed3fd24023b50c3423 and fixed in 6.18.38 with commit 1697957eb0971d420dde42862b88eb43506a1105 Issue introduced in 3.16 with commit b57708add31494175be741ed3fd24023b50c3423 and fixed in 7.1.3 with commit 47b5d3d506609b08b2e1f7c14f0b681a1953d572 Issue introduced in 3.16 with commit b57708add31494175be741ed3fd24023b50c3423 and fixed in 7.2-rc1 with commit 8165f7ff57d9667d2bb477ef6af83ede7fed4ad7 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-2026-63829 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/rtnetlink.h net/core/rtnetlink.c net/ipv4/ip_gre.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/9831bc9ecb402957810c2045c663fbfe9b09e296 https://git.kernel.org/stable/c/1697957eb0971d420dde42862b88eb43506a1105 https://git.kernel.org/stable/c/47b5d3d506609b08b2e1f7c14f0b681a1953d572 https://git.kernel.org/stable/c/8165f7ff57d9667d2bb477ef6af83ede7fed4ad7