CVE-2026-80978 json
net: cap advertised IP tunnel headroom
published 2026-09-11 58 d ago modified 2026-10-19 21 d ago also EUVD-2026-76301
- cvss
- 7.8
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.1%
- EPSS 0.1% chance of exploitation in 30 days, percentile 2%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- Linux Linux 5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.109, 6.18.50, 7.2.4, 7.3
- linux Debian 12 6.1.190-1
- linux Debian 13 6.12.111-1
- linux Debian 14 7.2.6-1
- linux-6.12 Debian 12 6.12.111-1~deb12u1
debian advisories DEBIAN-CVE-2026-80978
- linux Ubuntu 22.04 LTS 5.15.0-202.212
- linux Ubuntu 26.04 LTS 7.0.0-42.42
- linux-aws Ubuntu 22.04 LTS 5.15.0-1119.126
- linux-aws Ubuntu 26.04 LTS 7.0.0-1016.17
- linux-gcp Ubuntu 22.04 LTS 5.15.0-1120.130
- linux-gcp Ubuntu 26.04 LTS 7.0.0-1016.18
- linux-gke Ubuntu 22.04 LTS 5.15.0-1115.121
- linux-ibm Ubuntu 22.04 LTS 5.15.0-1113.117
ubuntu advisories UBUNTU-CVE-2026-80978
Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0
- kernel-source Linux Micro 6.0 6.4.0-159998.55.1
- kernel-default Linux Micro 6.0 6.4.0-159998.55.1
- kernel-kvmsmall Linux Micro 6.0 6.4.0-159998.55.1
- kernel-default-base Linux Micro 6.0 6.4.0-159998.55.1.159998.21.42
- kernel-64kb SLE Module for Basesystem 15 SP7 6.4.0-150700.53.90.1
- kernel-syms SLE Module for Development Tools 15 SP7 6.4.0-150700.53.90.1
- kernel-azure SLE Module for Public Cloud 15 SP7 6.4.0-150700.53.90.1
- kernel-source SLE Module for Development Tools 15 SP7, SLE Module for Basesystem 15 SP7 6.4.0-150700.53.90.1
suse advisories SUSE-SU-2026:5121-1SUSE-SU-2026:24550-1SUSE-SU-2026:5091-1
- kernel-source openSUSE Tumbleweed 7.2.6-1.1
opensuse advisories openSUSE-SU-2026:11805-1
- kernel Azure Linux 3.0 6.6.157.1-1
azure linux advisories AZL-100806
Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT
- git.kernel.org/stable/c/fb889a619723032140f5d983a3a34d25a5a2bed4 commit
- git.kernel.org/stable/c/b160422f8103574425e2834130e169d84c94fa1d commit
- git.kernel.org/stable/c/d36e75f5669140b66515ad3a176ca6337bd80a5e commit
- git.kernel.org/stable/c/84783961cb8bdb36b4f41a02ce43aafc6d52b176 commit
- git.kernel.org/stable/c/bc4e05ae66c9797a0972ac44326e69c5305e0020 commit
- git.kernel.org/stable/c/af0ee8f04bea22cdb331fa3509e17f81b48938ad commit
- git.kernel.org/stable/c/9144f2c53a04465a6878172b523f640313c5559e commit
- git.kernel.org/stable/c/6b222adeb9340306e2ff97127c76117abb9b3df8 commit
Vendor advisories
What the vendors themselves say about their products: affected, fixed or not affected, and what to do.
red hat product security vex CVE-2026-80978 updated cvss 5.5
kernel: net: cap advertised IP tunnel headroom
-
Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 moreaffected: workaround, no fix planned “Out of support scope”
-
Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-8, openshift/ose-rhel-coreos-9 Red Hat OpenShift Container Platform 5 openshift/ose-rhel-coreos-9affected: workaround, no fix available “Fix deferred”
Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- total
- Assessed
- 23 d ago
Exploit prediction
0.13% chance of exploitation in the next 30 days, higher than 2% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 7.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
Affected products
- Linux Linux
Classification
- Technology feeds
References
- git.kernel.org /stable/c/fb889a619723032140f5d983a3a34d25a5a2bed4
- git.kernel.org /stable/c/b160422f8103574425e2834130e169d84c94fa1d
- git.kernel.org /stable/c/d36e75f5669140b66515ad3a176ca6337bd80a5e
- git.kernel.org /stable/c/84783961cb8bdb36b4f41a02ce43aafc6d52b176
- git.kernel.org /stable/c/bc4e05ae66c9797a0972ac44326e69c5305e0020
- git.kernel.org /stable/c/af0ee8f04bea22cdb331fa3509e17f81b48938ad
- git.kernel.org /stable/c/9144f2c53a04465a6878172b523f640313c5559e
- git.kernel.org /stable/c/6b222adeb9340306e2ff97127c76117abb9b3df8
Sources
- CVE List CVE-2026-80978
- NVD CVE-2026-80978
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.