{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "1a37e412a0225fcba5587f24c0dfc7636efc8b69"
            },
            {
              "fixed": "fb889a619723032140f5d983a3a34d25a5a2bed4"
            },
            {
              "fixed": "b160422f8103574425e2834130e169d84c94fa1d"
            },
            {
              "fixed": "d36e75f5669140b66515ad3a176ca6337bd80a5e"
            },
            {
              "fixed": "84783961cb8bdb36b4f41a02ce43aafc6d52b176"
            },
            {
              "fixed": "bc4e05ae66c9797a0972ac44326e69c5305e0020"
            },
            {
              "fixed": "af0ee8f04bea22cdb331fa3509e17f81b48938ad"
            },
            {
              "fixed": "9144f2c53a04465a6878172b523f640313c5559e"
            },
            {
              "fixed": "6b222adeb9340306e2ff97127c76117abb9b3df8"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.11.0"
            },
            {
              "fixed": "5.10.270"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "5.11.0"
            },
            {
              "fixed": "5.15.221"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "5.16.0"
            },
            {
              "fixed": "6.1.188"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.2.0"
            },
            {
              "fixed": "6.6.157"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.7.0"
            },
            {
              "fixed": "6.12.109"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.13.0"
            },
            {
              "fixed": "6.18.50"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "7.2.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/80xxx/CVE-2026-80978.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: cap advertised IP tunnel headroom\n\nIP tunnel devices derive their advertised needed_headroom from lower\noutput devices. A stack of user-created devices can make the derived\nvalue larger than the 16-bit skb header offsets can represent. Once IP\noutput reserves it, skb head expansion can wrap those offsets.\n\nThe runtime transmit path already caps a growing needed_headroom at 512.\nApply the same cap when tunnel configuration publishes needed_headroom\nderived from a lower output device.\n\nCapping the advertised value is safe: IP tunnel transmit still expands\nthe skb when a packet needs more headroom. A nonsensical stacked\nconfiguration can therefore incur an extra reallocation, but it cannot\npublish an unbounded reservation to upper layers.",
  "id": "CVE-2026-80978",
  "modified": "2026-09-15T03:31:04.017769721Z",
  "published": "2026-09-11T19:42:39.496Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6b222adeb9340306e2ff97127c76117abb9b3df8"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/84783961cb8bdb36b4f41a02ce43aafc6d52b176"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9144f2c53a04465a6878172b523f640313c5559e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/af0ee8f04bea22cdb331fa3509e17f81b48938ad"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b160422f8103574425e2834130e169d84c94fa1d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/bc4e05ae66c9797a0972ac44326e69c5305e0020"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d36e75f5669140b66515ad3a176ca6337bd80a5e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/fb889a619723032140f5d983a3a34d25a5a2bed4"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/80xxx/CVE-2026-80978.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-80978"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "net: cap advertised IP tunnel headroom"
}