CVE-2026-98950 (GCVE-0-2026-98950)
Vulnerability from cvelistv5
Published
2026-10-23 12:19
Modified
2026-10-30 12:40
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: flow_dissector: avoid u16 truncation of hlen in bpf_flow_dissect() bpf_flow_dissect() sanitizes the offsets returned by the BPF program with clamp_t(u16, ..., hlen). If hlen is bigger than 65535, the upper bound is truncated before the comparison. For instance, with hlen == 65536, both nhoff and thoff are forced to zero, even if the program returned sane values. This is the same class of bug as the one fixed in commit 99bda1ecbd56 ("flow_dissector: avoid u16 truncation of skb->len when computing thoff"). That fix does not cover the BPF path, because __skb_flow_dissect() returns early when a BPF flow dissector handles the packet. struct bpf_flow_keys stores nhoff and thoff as u16, so cap hlen to U16_MAX before clamping. Found by sashiko while reviewing the commit above.
References
Impacted products
Vendor Product Version
Linux Linux Version: d58e468b1112dcd1d5193c0a89ff9f98b5a3e8b9
Version: d58e468b1112dcd1d5193c0a89ff9f98b5a3e8b9
Version: d58e468b1112dcd1d5193c0a89ff9f98b5a3e8b9
Version: d58e468b1112dcd1d5193c0a89ff9f98b5a3e8b9
Version: d58e468b1112dcd1d5193c0a89ff9f98b5a3e8b9
Version: d58e468b1112dcd1d5193c0a89ff9f98b5a3e8b9
Version: d58e468b1112dcd1d5193c0a89ff9f98b5a3e8b9
Version: d58e468b1112dcd1d5193c0a89ff9f98b5a3e8b9
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{
  "containers": {
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          "programFiles": [
            "net/core/flow_dissector.c"
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      "cpeApplicability": [
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              "operator": "OR"
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      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nflow_dissector: avoid u16 truncation of hlen in bpf_flow_dissect()\n\nbpf_flow_dissect() sanitizes the offsets returned by the BPF program\nwith clamp_t(u16, ..., hlen).\n\nIf hlen is bigger than 65535, the upper bound is truncated before\nthe comparison. For instance, with hlen == 65536, both nhoff and\nthoff are forced to zero, even if the program returned sane values.\n\nThis is the same class of bug as the one fixed in commit 99bda1ecbd56\n(\"flow_dissector: avoid u16 truncation of skb-\u003elen when computing\nthoff\"). That fix does not cover the BPF path, because\n__skb_flow_dissect() returns early when a BPF flow dissector\nhandles the packet.\n\nstruct bpf_flow_keys stores nhoff and thoff as u16, so cap hlen\nto U16_MAX before clamping.\n\nFound by sashiko while reviewing the commit above."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-30T12:40:29.247Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/46d21495f633e38d40857401504ee51c56ffed2a"
        },
        {
          "url": "https://git.kernel.org/stable/c/6267f8304cbd9ec9f3f53bd227a733e07131492e"
        },
        {
          "url": "https://git.kernel.org/stable/c/99c59062172620a0bac4ae8cf37c83bb78772cdd"
        },
        {
          "url": "https://git.kernel.org/stable/c/c44c02c930c6583b235a1937c69ff716c4bb4514"
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          "url": "https://git.kernel.org/stable/c/3fb5ad2951a6df92c98f4f06cd70f20c50a2eb2a"
        },
        {
          "url": "https://git.kernel.org/stable/c/cc18eb0e9941162c03f03f411ed7f6c339d91fa0"
        },
        {
          "url": "https://git.kernel.org/stable/c/61b43a51a55929ec040bee3ea51af2121b956d05"
        },
        {
          "url": "https://git.kernel.org/stable/c/f202578efc738b883cfa04889eb97328914265a7"
        }
      ],
      "title": "flow_dissector: avoid u16 truncation of hlen in bpf_flow_dissect()",
      "x_generator": {
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  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98950",
    "datePublished": "2026-10-23T12:19:09.890Z",
    "dateReserved": "2026-09-25T10:25:14.382Z",
    "dateUpdated": "2026-10-30T12:40:29.247Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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