CVE-2026-98554 (GCVE-0-2026-98554)
Vulnerability from cvelistv5
Published
2026-10-18 15:18
Modified
2026-10-19 09:21
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: vlan: ensure sufficient headroom in vlan_dev_hard_header() Callers that only reserve ETH_HLEN or less (such as llc_alloc_frame()), or skbs allocated before dynamic device/headroom changes (e.g. toggling VLAN_FLAG_REORDER_HDR or bonding/team switching slaves), can reach vlan_dev_hard_header() with insufficient headroom and trigger skb_under_panic(). Use skb_cow_head() in vlan_dev_hard_header() when VLAN_FLAG_REORDER_HDR is not set to ensure sufficient headroom for the VLAN header(s) and the underlying device hard header. Use READ_ONCE() to read dev->hard_header_len and dev->needed_headroom as they can be updated concurrently under RTNL (e.g. in vlan_transfer_features()) while vlan_dev_hard_header() runs locklessly on the transmit path. Also avoid LL_RESERVED_SPACE(dev) here so that the extra HH_DATA_MOD alignment padding does not trigger unnecessary pskb_expand_head() reallocations on inner stacked VLAN devices after the outer VLAN header has been pushed.
References
Impacted products
Vendor Product Version
Linux Linux Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
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{
  "containers": {
    "cna": {
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        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/8021q/vlan_dev.c"
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          "vendor": "Linux",
          "versions": [
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              "version": "0",
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      ],
      "cpeApplicability": [
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              "negate": false,
              "operator": "OR"
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      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nvlan: ensure sufficient headroom in vlan_dev_hard_header()\n\nCallers that only reserve ETH_HLEN or less (such as llc_alloc_frame()),\nor skbs allocated before dynamic device/headroom changes (e.g. toggling\nVLAN_FLAG_REORDER_HDR or bonding/team switching slaves), can reach\nvlan_dev_hard_header() with insufficient headroom and trigger\nskb_under_panic().\n\nUse skb_cow_head() in vlan_dev_hard_header() when VLAN_FLAG_REORDER_HDR\nis not set to ensure sufficient headroom for the VLAN header(s) and the\nunderlying device hard header.\n\nUse READ_ONCE() to read dev-\u003ehard_header_len and dev-\u003eneeded_headroom as\nthey can be updated concurrently under RTNL (e.g. in\nvlan_transfer_features()) while vlan_dev_hard_header() runs locklessly on\nthe transmit path. Also avoid LL_RESERVED_SPACE(dev) here so that the\nextra HH_DATA_MOD alignment padding does not trigger unnecessary\npskb_expand_head() reallocations on inner stacked VLAN devices after the\nouter VLAN header has been pushed."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:21:37.221Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/55e007fc3b4d76fa4d6b4660f6904fe6ab045a1b"
        },
        {
          "url": "https://git.kernel.org/stable/c/5aca8e6a8ff6aeae358c1d9b65447aac416ace95"
        },
        {
          "url": "https://git.kernel.org/stable/c/4ba1f57313f36a3ce6f77d593548f0c511f34aa1"
        },
        {
          "url": "https://git.kernel.org/stable/c/ca797491f0ae4bfde9039f79f6f1ed7781c9110f"
        },
        {
          "url": "https://git.kernel.org/stable/c/cfba0f45553de2b803059e3d539a1e418df24da8"
        },
        {
          "url": "https://git.kernel.org/stable/c/c7ee4bea64f559ea8e03260014775b64c720cb5b"
        },
        {
          "url": "https://git.kernel.org/stable/c/90d51095371d96747f45bbd8504edf6513e039ef"
        },
        {
          "url": "https://git.kernel.org/stable/c/cd5dd68267c4238795fadaf02b3575ca3f8a6500"
        }
      ],
      "title": "vlan: ensure sufficient headroom in vlan_dev_hard_header()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98554",
    "datePublished": "2026-10-18T15:18:21.751Z",
    "dateReserved": "2026-09-25T10:25:14.356Z",
    "dateUpdated": "2026-10-19T09:21:37.221Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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