net/openvswitch: check Ethernet header length in key_extract()

{
  "id": "52562cf6a371866d717553a07850fac304b6791c22c70fb5a88b1e5698a71fd6",
  "url": "https://osv.dev/vulnerability/CVE-2026-74701",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "net/openvswitch: check Ethernet header length in key_extract()",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: net/openvswitch: check Ethernet header length in key_extract() When a packet arrives on an ARPHRD_NONE device (e.g. TUN), ovs_flow_key_extract() trusts the user-provided skb->protocol field: if it is ETH_P_TEB, the packet is classified as MAC_PROTO_ETHERNET and key_extract() is called without ensuring the skb has ETH_HLEN (14) bytes of linear data. key_extract() unconditionally pulls 2 * ETH_ALEN bytes for MAC addresses and parse_ethertype() pulls 2 more, either of which triggers a kernel BUG in __skb_pull() when the linear area is too small. kernel BUG at include/linux/skbuff.h:2848! RIP: 0010:key_extract+0xa7e/0xd90 net/openvswitch/flow.c:933 ovs_flow_key_extract+0x419/0xa70 ovs_vport_receive+0x222/0x390 netdev_frame_hook+0x3e0/0x630 tun_get_user+0x2d0c/0x38e0 Fixed by calling check_header() in key_extract() before accessing the Ethernet header.",
    "evidence": "osv:CVE-2026-74701",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
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            "evidence": "/affected/1/ranges"
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            "evidence": "/affected/1/ranges"
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        "affected_versions": []
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    ],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-74701",
      "aliases": [
        "CVE-2026-74701"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
        }
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      ],
      "modified": "2026-10-28T02:30:48.985115876Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/0b60b55652ba772b173dddc63f3851e1d2dd5927",
        "https://git.kernel.org/stable/c/81f9b09f0ea3ba9ab966dd17e9f32625a14555e9",
        "https://git.kernel.org/stable/c/831471718f6e19aed1a330b03b53190a90e06466",
        "https://git.kernel.org/stable/c/9b8cfbb58b85bfa7a78fac47fdc77396cd01f699",
        "https://git.kernel.org/stable/c/a8139285c8925efe59af28a9169bb2fda91bff15",
        "https://git.kernel.org/stable/c/cf6f8b29befb92173659bcef6a441d274947bfae",
        "https://git.kernel.org/stable/c/d8bea341b183190ce6c055ab0e64ab78eb9a7290",
        "https://git.kernel.org/stable/c/e85278afd4890dd190ba3c7a1b1a712b801c9fe1",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74701.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-74701",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74701.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-74701",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 517546,
  "published_at": "2026-08-22T15:33:01.585+00:00"
}