{"id":"CVE-2026-72444","revision":"cb1f1de956b7404c9921bda6219e16ce","records":[{"revision":"cb1f1de956b7404c9921bda6219e16ce","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-72444","aliases":[],"title":"flow_dissector: check device type before reading ETH_ADDRS","description":"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 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.","state":0,"publishedAt":"2026-08-15T05:56:55.229+00:00","modifiedAt":"2026-10-16T18:55:24.524+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"net/core/flow_dissector.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"67a900cc0436d74e7ff89042371760def087680d\",\n                            \"lessThan\": \"0fe6455b8e1a22414f39c07bc90a1df12b52ec74\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"67a900cc0436d74e7ff89042371760def087680d\",\n                            \"lessThan\": \"9a65860959db594dfc1820c7fdc09285fb7556bf\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"67a900cc0436d74e7ff89042371760def087680d\",\n                            \"lessThan\": \"594c90b197141944f25991b8314de5c26ee27a7e\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"67a900cc0436d74e7ff89042371760def087680d\",\n                            \"lessThan\": \"c6d3bcb0f934d4297ac5fa1c8656ae40694fb601\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"67a900cc0436d74e7ff89042371760def087680d\",\n                            \"lessThan\": \"825de39f0c35a112148799b3cbe45af3766c018a\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"67a900cc0436d74e7ff89042371760def087680d\",\n                            \"lessThan\": \"bf6e8af2c8be77489bedeae9f8a9654cb710e500\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        }\n                    ]\n                }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"affected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"net/core/flow_dissector.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"4.2\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"4.2\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.1.178\",\n                            \"lessThanOrEqual\": \"6.1.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.6.145\",\n                            \"lessThanOrEqual\": \"6.6.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.12.97\",\n                            \"lessThanOrEqual\": \"6.12.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18.40\",\n                            \"lessThanOrEqual\": \"6.18.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.1.5\",\n                            \"lessThanOrEqual\": \"7.1.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.2\",\n                            \"lessThanOrEqual\": \"*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"original_commit_for_fix\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8,"severity":"HIGH"}],"references":["https://git.kernel.org/stable/c/0fe6455b8e1a22414f39c07bc90a1df12b52ec74","https://git.kernel.org/stable/c/9a65860959db594dfc1820c7fdc09285fb7556bf","https://git.kernel.org/stable/c/594c90b197141944f25991b8314de5c26ee27a7e","https://git.kernel.org/stable/c/c6d3bcb0f934d4297ac5fa1c8656ae40694fb601","https://git.kernel.org/stable/c/825de39f0c35a112148799b3cbe45af3766c018a","https://git.kernel.org/stable/c/bf6e8af2c8be77489bedeae9f8a9654cb710e500"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-72444","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-72444","identifiers":["CVE-2026-72444"]},"retained":false,"historicalAffected":[]}],"coverage":[]}