CVE-2026-80978

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.

CVSS v3 7.8 HIGH

7.8^/10

CVSS v3 : HIGH

Vector :

Exploitability : 1.8 / Impact : 5.9

Attack Vector LOCAL

Attack Complexity LOW

Privileges Required LOW

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://git.kernel.org/stable/c/6b222adeb9340306e2ff97127c76117abb9b3df8
https://git.kernel.org/stable/c/84783961cb8bdb36b4f41a02ce43aafc6d52b176
https://git.kernel.org/stable/c/9144f2c53a04465a6878172b523f640313c5559e
https://git.kernel.org/stable/c/af0ee8f04bea22cdb331fa3509e17f81b48938ad
https://git.kernel.org/stable/c/b160422f8103574425e2834130e169d84c94fa1d
https://git.kernel.org/stable/c/bc4e05ae66c9797a0972ac44326e69c5305e0020
https://git.kernel.org/stable/c/d36e75f5669140b66515ad3a176ca6337bd80a5e
https://git.kernel.org/stable/c/fb889a619723032140f5d983a3a34d25a5a2bed4

Configurations

No configuration.

History

No history.

Information

Published : 2026-09-11 20:19

Updated : 2026-09-14 13:18

NVD link : CVE-2026-80978

Mitre link : CVE-2026-80978

CVE.ORG link : CVE-2026-80978

JSON object : View

Products Affected

No product.

CWE

No CWE.

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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."}], "lastModified": "2026-09-14T13:18:52.650", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}