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 5B8EB58497D for ; Fri, 11 Sep 2026 19:56:18 +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=1789156591; cv=none; b=usw36wlZH+xweDldYf6nbxtY2IVpE9siOB53pMZW9L0pFT/bGJgWvSc+hWJwKOhCMVvYB0c2cW7G0+7gGvN/dq0kF/yGuDzLFXBrUc9Y+DdEmEG5JwT8EQ3XDjmFwrixibP+F7sMIVH+ftcTdmPZ2t2BXdJd+LbrLKtzE9MFMi8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789156591; c=relaxed/simple; bh=SOPJJkRKPbF4btJhy5S1HyLBdw7ToHROZRdD+bm3MfY=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=YWyOMIcozGkosF72frwZyDn/Dy6TDAyqOgxLWaCLg68PuKHGY/fHfVSQC3jGswA2LsjboGYIT+SRSiLpmP1GsZVrpNx3QopQHlfFsvbEMqJ669/isX0Nz256tu6QTCR6XhW4GvJ35NCkk0tjtG83Z/rxDBrzIocr6oVxvPzc0to= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=SEzDPwSC; 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="SEzDPwSC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0EC9E1F00893; Fri, 11 Sep 2026 19:56:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789156577; bh=x2SoqtpOEU5G6Js/TvGNRFSe8ywERDHc8t+n9ieGSmM=; h=From:To:Cc:Subject:Date:Reply-To; b=SEzDPwSC3WKLrGxdun2t6b2xMsSGDpSAILlfeowHPgdK0RJKqO4nEtmUQ4zHcGfZD M/ceQnjhVggLIca15L1VCkZ+TIhzJCHCzPnojQvN7dgnLC3OeyTQjI0JXJ5rdkw+eR yO+Qb0osBe7g/VmJEDHzUuYltOUSnxsvMZbRr73Q= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-89564: ip: orphan prefetched skbs before multicast forwarding Date: Fri, 11 Sep 2026 21:44:13 +0200 Message-ID: <2026091124-CVE-2026-89564-3694@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=2946; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=gTiwIk1ngaYzYUurueleMlY+XmqQ0MVXCm5N7FFTjOQ=; b=owGbwMvMwCRo6H6F97bub03G02pJDFlLIlNKyp5ND1uUwVlvmvGqhodb/qzA0/pU30vhx59ez i7jPdjTEcvCIMjEICumyPJlG8/R/RWHFL0MbU/DzGFlAhnCwMUpABPZyMgwP2n7nDVRU7jZUy9n B2xzTQ1K1Mp7wDA/52TLMpGqW78OVgpebtRYyOf7LowdAA== 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: ip: orphan prefetched skbs before multicast forwarding IPv4 and IPv6 input preserve an skb->sk association installed by bpf_sk_assign() so that local delivery can use the selected socket under RCU. Both address families can also prefetch a socket in UDP early demux. In both paths (BPF and UDP early demux) a reference is not guaranteed to be held on the socket. When a multicast packet is not locally deliverable, IPv6 hands the original skb to ip6_mr_input(). IPv4's ip_mr_input() similarly keeps the original skb when local delivery is not needed. Either path can put the skb on an unresolved multicast route queue or forward it after the receive-side RCU section ends. After the prefetched socket is destroyed, a later skb free invokes sock_pfree() and dereferences the stale skb->sk. Orphan the skb before each non-local multicast forwarding path. Local delivery retains the original skb; the existing skb_clone() calls provide multicast forwarding with a socket-free clone. The Linux kernel CVE team has assigned CVE-2026-89564 to this issue. Affected and fixed versions =========================== Issue introduced in 5.7 with commit cf7fbe660f2dbd738ab58aea8e9b0ca6ad232449 and fixed in 6.18.50 with commit a8af6fbac895f057c4b8ff8a2e3fb4c5827fe4ce Issue introduced in 5.7 with commit cf7fbe660f2dbd738ab58aea8e9b0ca6ad232449 and fixed in 7.2.4 with commit f1281d4b99089fbaf0d3579bba62a814ebb4de4d Issue introduced in 5.7 with commit cf7fbe660f2dbd738ab58aea8e9b0ca6ad232449 and fixed in 7.3-rc1 with commit e36ce6e78fe3fc3c071a26750783b7ba081ce10d 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-2026-89564 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/ipv4/ipmr.c net/ipv6/ip6_input.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/a8af6fbac895f057c4b8ff8a2e3fb4c5827fe4ce https://git.kernel.org/stable/c/f1281d4b99089fbaf0d3579bba62a814ebb4de4d https://git.kernel.org/stable/c/e36ce6e78fe3fc3c071a26750783b7ba081ce10d