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"
}
]
}
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Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
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- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
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- 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
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.
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