CVE-2026-98401

Kernel crash via stale tunnel transport-header offset

Published Oct 14, 2026 · Updated Oct 14, 2026

Out-of-bounds reading in Linux tunnel decapsulation allows attackers to crash the kernel via encapsulated packets carrying GSO metadata. Decapsulation leaves skb->transport_header pointing to the removed outer header; qdisc_pkt_len_segs_init() converts the negative offset to an unsigned length and reads beyond the packet buffer. The crash requires GSO metadata and bridge or HSR forwarding that bypasses the inner IP stack's header reset; attacker privileges and external network reachability are not established.

CVSS severityUnavailable
Unscored
EPSS probability0.21%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds reading in Linux tunnel decapsulation allows attackers to crash the kernel via encapsulated packets carrying GSO metadata. Decapsulation leaves skb->transport_header pointing to the removed outer header; qdisc_pkt_len_segs_init() converts the negative offset to an unsigned length and reads beyond the packet buffer. The crash requires GSO metadata and bridge or HSR forwarding that bypasses the inner IP stack's header reset; attacker privileges and external network reachability are not established.

The record

CVE
CVE-2026-98401
Published
Oct 14, 2026
Updated
Oct 14, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
Unavailable
Privileges
Unavailable

Timeline

How it unfolded

  1. Oct 14, 2026CVE publishedPublication date reported by the CVE source.
  2. Oct 14, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <28a57fb2c5df4deb42a06e52fd36c14b37aa0034
  2. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <3340b8565b85631cfeb0df049e8b46e3ef8bd7bd
  3. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <8c3d4dfcecf7670c1d752f1ae74b21b2af5feac1
  4. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <e4a5b01e59f7102169762b8f566c8e052d05c0ff
  5. Affected versionversion=2.6.12

What conditions does exploitation require?

Attack vectorUnavailable in this record.
Required privilegesUnavailable in this record.

What is affected?

The Linux Kernel Organization · Linuxversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <28a57fb2c5df4deb42a06e52fd36c14b37aa0034; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <3340b8565b85631cfeb0df049e8b46e3ef8bd7bd; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <8c3d4dfcecf7670c1d752f1ae74b21b2af5feac1; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <e4a5b01e59f7102169762b8f566c8e052d05c0ff; version=2.6.12

Published CVSS scores

No CVSS assessment is available in this record.

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Activity data is delayed. The latest report is Sep 28, 2026.

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No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
VectorUnavailable
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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