Tunnel routing loop triggers kernel warning in Linux flow offload
Key facts
- Attack vector
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- Privileges required
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- User interaction
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- Attack complexity
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- Impact type
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- Confidentiality · integrity · availability
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- Fix status
- Partial Red Hat: 2 without a fix
No CVSS vector from any source. Fix status from CNA and Red Hat.
Summary
The Linux kernel from 6.19 hits a kernel warning when a tunnel's route to its remote endpoint resolves back to the tunnel itself. The WARN_ON_ONCE check in dev_fill_forward_path() fires when a flowtable tries to offload a flow through that tunnel, and a user with CAP_NET_ADMIN can set up this routing loop.
Written with Claude Haiku 5.5 from the sources below · 2026-11-07
Description from the CNA
In the Linux kernel, the following vulnerability has been resolved: net: remove WARN_ON_ONCE() from the dev_fill_forward_path() loop check ipip_fill_forward_path() and ip6_tnl_fill_forward_path() look up the route to the tunnel's remote endpoint and set ctx->dev to its device, which is the tunnel itself when that route resolves back to the tunnel. dev_fill_forward_path() then makes no progress and trips WARN_ON_ONCE(last_dev == ctx->dev) as soon as a flowtable tries to offload a flow through the tunnel. That routing loop is a configuration any CAP_NET_ADMIN user can set up, and ip_tunnel_xmit() and ip6_tnl_xmit() already treat it as a tx error, so remove the warning and just fail the walk, as commit 008e7a7c293b ("net: remove WARN_ON_ONCE when accessing forward path array") did for the path stack overflow.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
Remediation
Upgrade the Linux kernel to 7.2.8 or 7.3. Red Hat rates this flaw Low, Red Hat Enterprise Linux 10 has no fix available, and Red Hat Enterprise Linux 6 has no fix planned.
Written with Claude Haiku 5.5 from the sources below · 2026-11-07
- Fix · CNA Linux (Linux) Fixed in 7.2.8, 7.3
Vendor assessments
Red Hat
Red Hat rating: Low. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 6 | Affected | No fix planned: Out of support scope |
Not affected: 5 products
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
- Red Hat OpenShift Container Platform 4
- Red Hat OpenShift Container Platform 5
Timeline
- 2026-10-06 Threatist record created from CVE-2026-98278
- 2026-10-06 Alias added: GHSA-6vfc-qfc9-vf68
- 2026-10-09 Affected versions changed · Red Hat
- 2026-10-09 CVSS score added · Red Hat
- 2026-10-19 Fix available: Linux/[email protected] · CNA
- 2026-11-07 Affected versions changed · Red Hat
References
More Linux vulnerabilities
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- TI-2021-02452 Incorrect authorization in Ubuntu linux kernel KEVCVSS 3.1HIGH 8.8
- TI-2013-05264 The (1) get_user and (2) put_user API functions in the Linux kernel before 3.5.5 on the… KEVCVSS 3.1HIGH 8.8
- TI-2022-00125 Integer overflow in kernel KEVCVSS 3.1HIGH 8.4
- TI-2013-01864 The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9… KEVCVSS 3.1HIGH 8.4
Sources
- CVE-2026-98278 · CVE Program
- CVE-2026-98278 · NVD
- FIRST EPSS
- GHSA-6vfc-qfc9-vf68 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-98278 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences