CVE-2026-98401: Linux kernel · net: iptunnel: fix stale transport header during tunnel decapsulation
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 7.5 High.
Data as of 27 Oct 2026, 09:02 UTC
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 14 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-gkepkg:deb/ubuntu/linux-gke?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
A fix is available that clears the transport_header offset in the GRO cell processing for all tunnel drivers, preventing the stale offset from causing kernel crashes. Users should apply the official Linux kernel patches that address this issue. Since this is a kernel-level vulnerability, updating to a patched kernel version is the recommended remediation. No additional mitigations are specifically required beyond applying the patch.
Description
CVE-2026-98401 is a vulnerability in the Linux kernel's iptunnel code where a stale transport header offset after tunnel decapsulation can cause a kernel crash. The issue arises when an encapsulated packet carrying GSO metadata is decapsulated, but the transport header offset is not properly reset, leading to an invalid memory access during packet processing. This can cause a kernel page fault and system instability. The vulnerability specifically affects scenarios involving GSO packets forwarded at layer 2 by a bridge or HSR. The fix involves clearing the transport header offset in the GRO cell processing for all tunnel drivers.
References
- ubuntu.com/security/CVE-2026-98401 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-98401 (opens in a new tab)
- git.kernel.org/stable/c/28a57fb2c5df4deb42a06e52fd36c14b37aa0034 (opens in a new tab)
- git.kernel.org/stable/c/e4a5b01e59f7102169762b8f566c8e052d05c0ff (opens in a new tab)
- git.kernel.org/stable/c/8c3d4dfcecf7670c1d752f1ae74b21b2af5feac1 (opens in a new tab)
- git.kernel.org/stable/c/3340b8565b85631cfeb0df049e8b46e3ef8bd7bd (opens in a new tab)