CVE-2026-80978net: cap advertised IP tunnel headroom
- 7.8HighCVSS base score
- 0.13%Exploitation in 30 daysEPSS · top 97% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
In 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.
Timeline
ID reserved
By Linux
- 16 days later
· 16 days later
Published
- 38 days later
· 38 days later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| LinuxCNA (assigner) | 3.1 | High7.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| NVDNVD · Received | 3.1 | High7.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 0.13% · top 97% of all CVEs (12 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: total
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.8.
Affected products
- affected 1a37e412a0225fcba5587f24c0dfc7636efc8b69 – < fb889a619723032140f5d983a3a34d25a5a2bed4
- affected 1a37e412a0225fcba5587f24c0dfc7636efc8b69 – < b160422f8103574425e2834130e169d84c94fa1d
- affected 1a37e412a0225fcba5587f24c0dfc7636efc8b69 – < d36e75f5669140b66515ad3a176ca6337bd80a5e
- affected 1a37e412a0225fcba5587f24c0dfc7636efc8b69 – < 84783961cb8bdb36b4f41a02ce43aafc6d52b176
- affected 1a37e412a0225fcba5587f24c0dfc7636efc8b69 – < bc4e05ae66c9797a0972ac44326e69c5305e0020
- affected 1a37e412a0225fcba5587f24c0dfc7636efc8b69 – < af0ee8f04bea22cdb331fa3509e17f81b48938ad
- affected 1a37e412a0225fcba5587f24c0dfc7636efc8b69 – < 9144f2c53a04465a6878172b523f640313c5559e
- affected 1a37e412a0225fcba5587f24c0dfc7636efc8b69 – < 6b222adeb9340306e2ff97127c76117abb9b3df8
- affected 3.11
- unaffected < 3.11
- unaffected 5.10.270 – ≤ 5.10.*
- unaffected 5.15.221 – ≤ 5.15.*
- unaffected 6.1.188 – ≤ 6.1.*
- unaffected 6.6.157 – ≤ 6.6.*
- unaffected 6.12.109 – ≤ 6.12.*
- unaffected 6.18.50 – ≤ 6.18.*
- unaffected 7.2.4 – ≤ 7.2.*
- unaffected 7.3 – ≤ *
References
References8
- https://git.kernel.org/stable/c/fb889a619723032140f5d983a3a34d25a5a2bed4 (opens in a new tab)
- https://git.kernel.org/stable/c/b160422f8103574425e2834130e169d84c94fa1d (opens in a new tab)
- https://git.kernel.org/stable/c/d36e75f5669140b66515ad3a176ca6337bd80a5e (opens in a new tab)
- https://git.kernel.org/stable/c/84783961cb8bdb36b4f41a02ce43aafc6d52b176 (opens in a new tab)
- https://git.kernel.org/stable/c/bc4e05ae66c9797a0972ac44326e69c5305e0020 (opens in a new tab)
- https://git.kernel.org/stable/c/af0ee8f04bea22cdb331fa3509e17f81b48938ad (opens in a new tab)
- https://git.kernel.org/stable/c/9144f2c53a04465a6878172b523f640313c5559e (opens in a new tab)
- https://git.kernel.org/stable/c/6b222adeb9340306e2ff97127c76117abb9b3df8 (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-76301 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-80978)Record last updated .