GHSA-P2QP-RM9G-W8F3
Vulnerability from github – Published: 2026-09-11 21:31 – Updated: 2026-09-14 15:32In the Linux kernel, the following vulnerability has been resolved:
net: cap advertised IP tunnel headroom
IP tunnel devices derive their advertised needed_headroom from lower output devices. A stack of user-created devices can make the derived value larger than the 16-bit skb header offsets can represent. Once IP output reserves it, skb head expansion can wrap those offsets.
The runtime transmit path already caps a growing needed_headroom at 512. Apply the same cap when tunnel configuration publishes needed_headroom derived from a lower output device.
Capping the advertised value is safe: IP tunnel transmit still expands the skb when a packet needs more headroom. A nonsensical stacked configuration can therefore incur an extra reallocation, but it cannot publish an unbounded reservation to upper layers.
{
"affected": [],
"aliases": [
"CVE-2026-80978"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-11T20:19:04Z",
"severity": "HIGH"
},
"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": "GHSA-p2qp-rm9g-w8f3",
"modified": "2026-09-14T15:32:21Z",
"published": "2026-09-11T21:31:22Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-80978"
},
{
"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"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
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- Confirmed: The vulnerability has been validated from an analyst's perspective.
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- 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.
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