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NVD / CVE Program· CNA Linux

CVE-2026-80978: net: cap advertised IP tunnel headroom

Noroxi assessment

Priority: Monitor (action score 31/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.12% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 6b222adeb9340306e2ff97127c76117abb9b3df8, 84783961cb8bdb36b4f41a02ce43aafc6d52b176, 9144f2c53a04465a6878172b523f640313c5559e.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 6b222adeb9340306e2ff97127c76117abb9b3df8, 84783961cb8bdb36b4f41a02ce43aafc6d52b176, 9144f2c53a04465a6878172b523f640313c5559e or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

HighCVSS 7.8 · v3.1—No exploit Fix available
Published
Sep 11, 2026
Updated
Oct 19, 2026
EPSS
0.1% · 2th percentile
CWE
—

Report tools

JSON

Action score

31

Monitor

Low priority for now.

CVSS
31 / 40 · 7.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Linux
7.8
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-80978

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 3.11affected
    • 1a37e412a0225fcba5587f24c0dfc7636efc8b69 and later · before fb889a619723032140f5d983a3a34d25a5a2bed4affected · git
    • 1a37e412a0225fcba5587f24c0dfc7636efc8b69 and later · before b160422f8103574425e2834130e169d84c94fa1daffected · git
    • 1a37e412a0225fcba5587f24c0dfc7636efc8b69 and later · before d36e75f5669140b66515ad3a176ca6337bd80a5eaffected · git
    • 1a37e412a0225fcba5587f24c0dfc7636efc8b69 and later · before 84783961cb8bdb36b4f41a02ce43aafc6d52b176affected · git
    • 1a37e412a0225fcba5587f24c0dfc7636efc8b69 and later · before bc4e05ae66c9797a0972ac44326e69c5305e0020affected · git
    • 1a37e412a0225fcba5587f24c0dfc7636efc8b69 and later · before af0ee8f04bea22cdb331fa3509e17f81b48938adaffected · git
    • 1a37e412a0225fcba5587f24c0dfc7636efc8b69 and later · before 9144f2c53a04465a6878172b523f640313c5559eaffected · git
    • 1a37e412a0225fcba5587f24c0dfc7636efc8b69 and later · before 6b222adeb9340306e2ff97127c76117abb9b3df8affected · git
    • before 3.11not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.190-16.1.190-1
Debian:12linux-6.12before 6.12.111-1~deb12u16.12.111-1~deb12u1
Debian:13linuxbefore 6.12.111-16.12.111-1
Debian:14linuxbefore 7.2.6-17.2.6-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-80976Sep 11, 2026 · seg6: reset IP6CB after IPv6 decapsulation
    39Monitor
  • ← EarlierCVE-2026-80977Sep 11, 2026 · net: skbuff: don't touch shared zerocopy state in skb_tx_error()
    31Monitor
  • Later →CVE-2026-80979Sep 11, 2026 · net/smc: unregister the connection before draining the rx tasklet
    31Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux6b222adeb9340306e2ff97127c76117abb9b3df8Vendor (CNA)
Linux Linux84783961cb8bdb36b4f41a02ce43aafc6d52b176Vendor (CNA)
Linux Linux9144f2c53a04465a6878172b523f640313c5559eVendor (CNA)
Linux Linuxaf0ee8f04bea22cdb331fa3509e17f81b48938adVendor (CNA)
Linux Linuxb160422f8103574425e2834130e169d84c94fa1dVendor (CNA)
Linux Linuxbc4e05ae66c9797a0972ac44326e69c5305e0020Vendor (CNA)
Linux Linuxd36e75f5669140b66515ad3a176ca6337bd80a5eVendor (CNA)
Linux Linuxfb889a619723032140f5d983a3a34d25a5a2bed4Vendor (CNA)
debian:linux6.1.190-1 · Debian:12Package registry (OSV)
debian:linux6.12.111-1 · Debian:13Package registry (OSV)
debian:linux-6.126.12.111-1~deb12u1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

—

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. SSVC exploitation— → none
  2. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (7 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records