CVE-2026-98554 (GCVE-0-2026-98554)

Vulnerability from cvelistv5 – Published: 2026-10-18 15:18 – Updated: 2026-10-19 09:21
VLAI
Title
vlan: ensure sufficient headroom in vlan_dev_hard_header()
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.
Severity
No CVSS data available.
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 6643 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 55e007fc3b4d76fa4d6b4660f6904fe6ab045a1b (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 5aca8e6a8ff6aeae358c1d9b65447aac416ace95 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 4ba1f57313f36a3ce6f77d593548f0c511f34aa1 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < ca797491f0ae4bfde9039f79f6f1ed7781c9110f (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < cfba0f45553de2b803059e3d539a1e418df24da8 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < c7ee4bea64f559ea8e03260014775b64c720cb5b (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 90d51095371d96747f45bbd8504edf6513e039ef (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < cd5dd68267c4238795fadaf02b3575ca3f8a6500 (git)
guessed Create a notification for this product.
Linux Linux Affected: 2.6.12
Unaffected: 0 , < 2.6.12 (semver)
Unaffected: 5.10.271 , ≤ 5.10.* (semver)
Unaffected: 5.15.222 , ≤ 5.15.* (semver)
Unaffected: 6.1.189 , ≤ 6.1.* (semver)
Unaffected: 6.6.158 , ≤ 6.6.* (semver)
Unaffected: 6.12.112 , ≤ 6.12.* (semver)
Unaffected: 6.18.55 , ≤ 6.18.* (semver)
Unaffected: 7.2.9 , ≤ 7.2.* (semver)
Unaffected: 7.3 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
Show details on NVD website
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{
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          "programFiles": [
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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\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": [
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          "url": "https://git.kernel.org/stable/c/55e007fc3b4d76fa4d6b4660f6904fe6ab045a1b"
        },
        {
          "url": "https://git.kernel.org/stable/c/5aca8e6a8ff6aeae358c1d9b65447aac416ace95"
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        },
        {
          "url": "https://git.kernel.org/stable/c/cd5dd68267c4238795fadaf02b3575ca3f8a6500"
        }
      ],
      "title": "vlan: ensure sufficient headroom in vlan_dev_hard_header()",
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    "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"
  },
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      "date": "2026-11-10",
      "epss": "0.00216",
      "percentile": "0.12176"
    },
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      "product_status:fixed": "1",
      "product_status:known_affected": "1",
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      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "vlan: ensure sufficient headroom in vlan_dev_hard_header()",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-98554.json",
      "version": "5"
    },
    "nvd": {
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        "cveTags": [],
        "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."
          }
        ],
        "id": "CVE-2026-98554",
        "lastModified": "2026-10-19T10:19:11.773",
        "metrics": {},
        "published": "2026-10-18T16:17:07.490",
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          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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          },
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            "url": "https://git.kernel.org/stable/c/ca797491f0ae4bfde9039f79f6f1ed7781c9110f"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/cd5dd68267c4238795fadaf02b3575ca3f8a6500"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/cfba0f45553de2b803059e3d539a1e418df24da8"
          }
        ],
        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-11-07T11:30:38+00:00",
      "cve": "CVE-2026-98554",
      "id": "CVE-2026-98554",
      "initial_release_date": "2026-10-18T00:00:00+00:00",
      "product_status:known_affected": "203",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: vlan: ensure sufficient headroom in vlan_dev_hard_header()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-98554.json",
      "version": "3"
    }
  }
}



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  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

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How durations are calculated

Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.

Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.

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