{"id":"CVE-2026-72444","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nflow_dissector: check device type before reading ETH_ADDRS\n\n__skb_flow_dissect() unconditionally reads 12 bytes from eth_hdr(skb)\nwhen FLOW_DISSECTOR_KEY_ETH_ADDRS is r…","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nflow_dissector: check device type before reading ETH_ADDRS\n\n__skb_flow_dissect() unconditionally reads 12 bytes from eth_hdr(skb)\nwhen FLOW_DISSECTOR_KEY_ETH_ADDRS is r…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cwe":["CWE-20"],"vendor":"Red Hat","product":"Red Hat Enterprise Linux 9","affected":["enterprise_linux 10","enterprise_linux 6","enterprise_linux 7","enterprise_linux 8","enterprise_linux 9"],"published":"2026-08-15","updated":"2026-10-16","sourceUpdated":"2026-10-16T19:17:30.897","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-72444","references":[{"url":"https://git.kernel.org/stable/c/0fe6455b8e1a22414f39c07bc90a1df12b52ec74","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/594c90b197141944f25991b8314de5c26ee27a7e","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/825de39f0c35a112148799b3cbe45af3766c018a","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/9a65860959db594dfc1820c7fdc09285fb7556bf","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/bf6e8af2c8be77489bedeae9f8a9654cb710e500","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/c6d3bcb0f934d4297ac5fa1c8656ae40694fb601","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-72444.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-72444"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2516571"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-72444"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-72444"},{"url":"https://kernelcve.org/list/?q=CVE-2026-72444"},{"url":"https://lore.kernel.org/linux-cve-announce/2026081530-CVE-2026-72444-103f@gregkh/T"}],"tags":["nvd","csaf","vex","red-hat","cve.org","score-dispute"],"epss":0.00129,"epssPercentile":0.02549,"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-10-16T18:50:08.470597Z"},"scores":{"nvd":7.8,"vendor":5.5,"cna":7.8},"ingestedAt":"2026-10-16T19:46:24.395Z","slug":"CVE-2026-72444","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nflow_dissector: check device type before reading ETH_ADDRS\n\n__skb_flow_dissect() unconditionally reads 12 bytes from eth_hdr(skb)\nwhen FLOW_DISSECTOR_KEY_ETH_ADDRS is requested. This assumes the skb\nhas a valid Ethernet header at mac_header, which is not always the case.\n\nThe problem can be triggered by:\n 1. Creating a TUN device in L3 mode (IFF_TUN, hard_header_len=0)\n 2. Attaching a multiq qdisc with a flower filter matching on eth_src\n 3. Sending a packet through AF_PACKET\n\nSince TUN in L3 mode has no link-layer header, mac_header points to\nthe L3 data area. The flow dissector reads 12 bytes of uninitialized\nskb memory, which then propagates through fl_set_masked_key() and is\nused as a rhashtable lookup key in __fl_lookup(), as reported by KMSAN.\n\nRejecting the filter in the control path (at tc filter add time) is\nnot feasible because TC filter blocks can be shared between arbitrary\ndevices -- a filter installed on an Ethernet device may later classify\npackets on a headerless device through a shared block. The device\nassociation is not fixed at filter creation time.\n\nFix this by gating the memcpy on dev->type == ARPHRD_ETHER, which\nensures only true Ethernet-framed packets have their addresses read.\nThis is more precise than the previous hard_header_len >= 12 check,\nwhich would incorrectly pass for non-Ethernet link types like IPoIB\n(ARPHRD_INFINIBAND, hard_header_len=24) and FDDI (hard_header_len=21)\nwhose L2 headers are not in Ethernet format. Additionally check\nskb_mac_header_was_set() to guard against the pathological case where\nmac_header is the unset sentinel (~0U), which would cause eth_hdr() to\nreturn a wild pointer.\n\nFor the act_mirred redirect case (Ethernet packet redirected to a\nnon-Ethernet device sharing a TC block), zeroing the key is the correct\nbehavior: the packet is now being classified on the target device, where\nEthernet address matching is not semantically meaningful.\n\nNote: on non-Ethernet devices, the zeroed key will match a filter\nconfigured with all-zero MAC addresses. This is an improvement over the\nprevious behavior where uninitialized memory could randomly match any\nfilter.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9 · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, … · updated 2026-10-26 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-72444.json)","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":230307,"id":"CVE-2026-72444","ts":1793130916730,"field":"cvss","old":"5.5","new":"7.8"},{"seq":230306,"id":"CVE-2026-72444","ts":1793130916730,"field":"severity","old":"medium","new":"high"},{"seq":229328,"id":"CVE-2026-72444","ts":1793019688916,"field":"cvss","old":"7.8","new":"5.5"},{"seq":229327,"id":"CVE-2026-72444","ts":1793019688916,"field":"severity","old":"high","new":"medium"}]}