{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/core/flow_dissector.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "0fe6455b8e1a22414f39c07bc90a1df12b52ec74",
              "status": "affected",
              "version": "67a900cc0436d74e7ff89042371760def087680d",
              "versionType": "git"
            },
            {
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              "status": "affected",
              "version": "67a900cc0436d74e7ff89042371760def087680d",
              "versionType": "git"
            },
            {
              "lessThan": "594c90b197141944f25991b8314de5c26ee27a7e",
              "status": "affected",
              "version": "67a900cc0436d74e7ff89042371760def087680d",
              "versionType": "git"
            },
            {
              "lessThan": "c6d3bcb0f934d4297ac5fa1c8656ae40694fb601",
              "status": "affected",
              "version": "67a900cc0436d74e7ff89042371760def087680d",
              "versionType": "git"
            },
            {
              "lessThan": "825de39f0c35a112148799b3cbe45af3766c018a",
              "status": "affected",
              "version": "67a900cc0436d74e7ff89042371760def087680d",
              "versionType": "git"
            },
            {
              "lessThan": "bf6e8af2c8be77489bedeae9f8a9654cb710e500",
              "status": "affected",
              "version": "67a900cc0436d74e7ff89042371760def087680d",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/core/flow_dissector.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.2"
            },
            {
              "lessThan": "4.2",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.178",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.145",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.97",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.40",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.5",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.178",
                  "versionStartIncluding": "4.2",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.145",
                  "versionStartIncluding": "4.2",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.97",
                  "versionStartIncluding": "4.2",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.40",
                  "versionStartIncluding": "4.2",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.5",
                  "versionStartIncluding": "4.2",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "4.2",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "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-\u003etype == ARPHRD_ETHER, which\nensures only true Ethernet-framed packets have their addresses read.\nThis is more precise than the previous hard_header_len \u003e= 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."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The bug is hit from TC flower classification (fl_classify) on packets injected locally via AF_PACKET through an L3 TUN with mq/flower qdisc; per kernel guidance TC/netlink qdisc paths are Local, not remotely reachable network stack handlers.\nAC:L - Syzbot and the fix commit show reliable reproduction by creating an L3 TUN, attaching a multiq qdisc with a flower eth_src filter, and sending packets via AF_PACKET; the attacker controls every setup step with no races or rare kernel config.\nPR:L - Exploitation requires CAP_NET_ADMIN to create/configure the TUN and install TC flower filters via rtnetlink, plus CAP_NET_RAW for AF_PACKET sockets; both capabilities are obtainable by an unprivileged user inside a user+network namespace (unshare -Urn).\nUI:N - No victim user action is required; exploitation uses attacker-controlled local syscalls (TUN ioctl, rtnetlink TC setup, AF_PACKET sendmsg) in a namespace they create.\nS:U - Impact stays within the kernel networking/TC subsystem of the host or attacker-controlled namespace; it does not cross VM, sandbox, or IOMMU security boundaries.\nC:H - __skb_flow_dissect copies 12 bytes from eth_hdr(skb) when FLOW_DISSECTOR_KEY_ETH_ADDRS is set; on headerless devices (L3 TUN, ARPHRD_NONE) mac_header points at L3 data or unset headroom, leaking uninitialized or out-of-bounds kernel memory into flow keys used by __fl_lookup.\nI:H - Garbage eth address keys flow through fl_set_masked_key into rhashtable lookup and can spuriously match flower filters, invoking unintended TC actions (police drop, skb mark, act_mirred redirect) that alter packet handling beyond the attacker\u0027s own data.\nA:H - When mac_header is the unset sentinel (~0U), eth_hdr() becomes a wild pointer and the memcpy can page-fault with a kernel oops/panic; even without fault, mis-matched filters can apply drop/redirect actions that deny or disrupt packet delivery."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T05:44:16.441Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/0fe6455b8e1a22414f39c07bc90a1df12b52ec74"
        },
        {
          "url": "https://git.kernel.org/stable/c/9a65860959db594dfc1820c7fdc09285fb7556bf"
        },
        {
          "url": "https://git.kernel.org/stable/c/594c90b197141944f25991b8314de5c26ee27a7e"
        },
        {
          "url": "https://git.kernel.org/stable/c/c6d3bcb0f934d4297ac5fa1c8656ae40694fb601"
        },
        {
          "url": "https://git.kernel.org/stable/c/825de39f0c35a112148799b3cbe45af3766c018a"
        },
        {
          "url": "https://git.kernel.org/stable/c/bf6e8af2c8be77489bedeae9f8a9654cb710e500"
        }
      ],
      "title": "flow_dissector: check device type before reading ETH_ADDRS",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-72444",
    "datePublished": "2026-08-15T05:56:55.229Z",
    "dateReserved": "2026-08-09T03:40:39.930Z",
    "dateUpdated": "2026-08-17T05:44:16.441Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}