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CVE-2026-80978

7.8 · HIGH

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.

Published Sep 11, 2026EPSS 0.13%

Overview

CVE-2026-80978 is a high-severity vulnerability. It was published on September 11, 2026 and has a CVSS 3.1 base score of 7.8 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.8, rated HIGH. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refgit.kernel.org/stable/c/6b222adeb9340306e2ff97127c76117abb9b3df8Refgit.kernel.org/stable/c/84783961cb8bdb36b4f41a02ce43aafc6d52b176Refgit.kernel.org/stable/c/9144f2c53a04465a6878172b523f640313c5559eRefgit.kernel.org/stable/c/af0ee8f04bea22cdb331fa3509e17f81b48938adRefgit.kernel.org/stable/c/b160422f8103574425e2834130e169d84c94fa1dRefgit.kernel.org/stable/c/bc4e05ae66c9797a0972ac44326e69c5305e0020Refgit.kernel.org/stable/c/d36e75f5669140b66515ad3a176ca6337bd80a5eRefgit.kernel.org/stable/c/fb889a619723032140f5d983a3a34d25a5a2bed4

How CyberStrike helps

Frequently asked questions

What is CVE-2026-80978?

CVE-2026-80978 is a high-severity vulnerability. It was published on September 11, 2026 and has a CVSS 3.1 base score of 7.8 (HIGH).

How severe is CVE-2026-80978?

This vulnerability has a CVSS 3.1 base score of 7.8, rated HIGH. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2026-80978?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-80978?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-80978 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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