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CVE-2026-80925 (GCVE-0-2026-80925)

Vulnerability from cvelistv5 – Published: 2026-09-09 16:19 – Updated: 2026-09-11 09:57
VLAI
Title
vlan: fix skb_under_panic and races when toggling HW VLAN offload
Summary
In the Linux kernel, the following vulnerability has been resolved: vlan: fix skb_under_panic and races when toggling HW VLAN offload Toggling hardware VLAN TX offload (NETIF_F_HW_VLAN_CTAG_TX or NETIF_F_HW_VLAN_STAG_TX) on a lower device invokes vlan_transfer_features(), which dynamically changed vlandev->hard_header_len. This causes two issues: 1. Lockless TX paths (e.g. packet_snd in af_packet.c, ip6_finish_output2) read dev->hard_header_len without holding RTNL lock. Mutating hard_header_len dynamically under RTNL creates a data race where upper layers reserve insufficient headroom based on a stale hard_header_len, resulting in skb_under_panic when vlan_dev_hard_header() is called. 2. In addition, vlan_transfer_features() updated hard_header_len without updating header_ops, causing a mismatch between allocated headroom and header creation. Always setting dev->hard_header_len = real_dev->hard_header_len and dev->needed_headroom = real_dev->needed_headroom + VLAN_HLEN unconditionally ensures: - dev->hard_header_len remains 100% static and immutable at real_dev->hard_header_len, eliminating all dynamic runtime updates and data races on hard_header_len. - Upper layers allocating skbs via LL_RESERVED_SPACE() will always reserve sufficient headroom for software VLAN tag insertion (real_dev->hard_header_len + real_dev->needed_headroom + VLAN_HLEN). - vlandev inherits real_dev->needed_tailroom so underlying trailer/padding/ICV requirements are honored. - AF_PACKET SOCK_RAW network header offsets remain correctly aligned at real_dev->hard_header_len. - vlan_header_ops is used unconditionally. Note to stable teams: Make sure to backport these commits: e16e960d55a4 ("ipvlan: inherit needed_headroom and needed_tailroom from phy_dev") cef51860becd ("macvlan: inherit needed_headroom and needed_tailroom from lowerdev")
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 1517d1996b5236fe69eccd9d253f725e06996eb1 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < a29f3b884ba50217e6f50414f568073221e2bb07 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 447cbe95ebb95392b5d8f6a01c0556826919ce23 (git)
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Linux Linux Affected: 2.6.12
Unaffected: 0 , < 2.6.12 (semver)
Unaffected: 6.18.51 , ≤ 6.18.* (semver)
Unaffected: 7.2.3 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/8021q/vlan_dev.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
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              "status": "affected",
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              "versionType": "git"
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          "vendor": "Linux",
          "versions": [
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              "version": "2.6.12"
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              "version": "0",
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              "versionType": "semver"
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              "version": "7.2.3",
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              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nvlan: fix skb_under_panic and races when toggling HW VLAN offload\n\nToggling hardware VLAN TX offload (NETIF_F_HW_VLAN_CTAG_TX or\nNETIF_F_HW_VLAN_STAG_TX) on a lower device invokes vlan_transfer_features(),\nwhich dynamically changed vlandev-\u003ehard_header_len.\n\nThis causes two issues:\n1. Lockless TX paths (e.g. packet_snd in af_packet.c, ip6_finish_output2)\n   read dev-\u003ehard_header_len without holding RTNL lock. Mutating\n   hard_header_len dynamically under RTNL creates a data race where upper\n   layers reserve insufficient headroom based on a stale hard_header_len,\n   resulting in skb_under_panic when vlan_dev_hard_header() is called.\n2. In addition, vlan_transfer_features() updated hard_header_len without\n   updating header_ops, causing a mismatch between allocated headroom\n   and header creation.\n\nAlways setting dev-\u003ehard_header_len = real_dev-\u003ehard_header_len and\ndev-\u003eneeded_headroom = real_dev-\u003eneeded_headroom + VLAN_HLEN unconditionally\nensures:\n- dev-\u003ehard_header_len remains 100% static and immutable at real_dev-\u003ehard_header_len,\n  eliminating all dynamic runtime updates and data races on hard_header_len.\n- Upper layers allocating skbs via LL_RESERVED_SPACE() will always reserve\n  sufficient headroom for software VLAN tag insertion (real_dev-\u003ehard_header_len +\n  real_dev-\u003eneeded_headroom + VLAN_HLEN).\n- vlandev inherits real_dev-\u003eneeded_tailroom so underlying trailer/padding/ICV\n  requirements are honored.\n- AF_PACKET SOCK_RAW network header offsets remain correctly aligned at\n  real_dev-\u003ehard_header_len.\n- vlan_header_ops is used unconditionally.\n\nNote to stable teams: Make sure to backport these commits:\n\ne16e960d55a4 (\"ipvlan: inherit needed_headroom and needed_tailroom from phy_dev\")\ncef51860becd (\"macvlan: inherit needed_headroom and needed_tailroom from lowerdev\")"
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-11T09:57:24.254Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/1517d1996b5236fe69eccd9d253f725e06996eb1"
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          "url": "https://git.kernel.org/stable/c/a29f3b884ba50217e6f50414f568073221e2bb07"
        },
        {
          "url": "https://git.kernel.org/stable/c/447cbe95ebb95392b5d8f6a01c0556826919ce23"
        }
      ],
      "title": "vlan: fix skb_under_panic and races when toggling HW VLAN offload",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-80925",
    "datePublished": "2026-09-09T16:19:44.748Z",
    "dateReserved": "2026-08-26T14:34:25.802Z",
    "dateUpdated": "2026-09-11T09:57:24.254Z",
    "state": "PUBLISHED"
  },
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  "dataVersion": "5.2",
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      "date": "2026-09-18",
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      "percentile": "0.05017"
    },
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      "product_status:known_affected": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "vlan: fix skb_under_panic and races when toggling HW VLAN offload",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-80925.json",
      "version": "1"
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                ],
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        "descriptions": [
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            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nvlan: fix skb_under_panic and races when toggling HW VLAN offload\n\nToggling hardware VLAN TX offload (NETIF_F_HW_VLAN_CTAG_TX or\nNETIF_F_HW_VLAN_STAG_TX) on a lower device invokes vlan_transfer_features(),\nwhich dynamically changed vlandev-\u003ehard_header_len.\n\nThis causes two issues:\n1. Lockless TX paths (e.g. packet_snd in af_packet.c, ip6_finish_output2)\n   read dev-\u003ehard_header_len without holding RTNL lock. Mutating\n   hard_header_len dynamically under RTNL creates a data race where upper\n   layers reserve insufficient headroom based on a stale hard_header_len,\n   resulting in skb_under_panic when vlan_dev_hard_header() is called.\n2. In addition, vlan_transfer_features() updated hard_header_len without\n   updating header_ops, causing a mismatch between allocated headroom\n   and header creation.\n\nAlways setting dev-\u003ehard_header_len = real_dev-\u003ehard_header_len and\ndev-\u003eneeded_headroom = real_dev-\u003eneeded_headroom + VLAN_HLEN unconditionally\nensures:\n- dev-\u003ehard_header_len remains 100% static and immutable at real_dev-\u003ehard_header_len,\n  eliminating all dynamic runtime updates and data races on hard_header_len.\n- Upper layers allocating skbs via LL_RESERVED_SPACE() will always reserve\n  sufficient headroom for software VLAN tag insertion (real_dev-\u003ehard_header_len +\n  real_dev-\u003eneeded_headroom + VLAN_HLEN).\n- vlandev inherits real_dev-\u003eneeded_tailroom so underlying trailer/padding/ICV\n  requirements are honored.\n- AF_PACKET SOCK_RAW network header offsets remain correctly aligned at\n  real_dev-\u003ehard_header_len.\n- vlan_header_ops is used unconditionally.\n\nNote to stable teams: Make sure to backport these commits:\n\ne16e960d55a4 (\"ipvlan: inherit needed_headroom and needed_tailroom from phy_dev\")\ncef51860becd (\"macvlan: inherit needed_headroom and needed_tailroom from lowerdev\")"
          }
        ],
        "id": "CVE-2026-80925",
        "lastModified": "2026-09-11T10:16:52.437",
        "metrics": {},
        "published": "2026-09-09T17:17:47.763",
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            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
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    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-09-11T01:03:27Z",
      "cve": "CVE-2026-80925",
      "id": "CVE-2026-80925",
      "initial_release_date": "2026-09-10T01:49:31Z",
      "product_status:known_affected": "349",
      "product_status:known_not_affected": "4",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-80925",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-80925.json",
      "version": "3"
    }
  }
}



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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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