CVE Catalog

CVE-2026-98278

Low risk· EPSS 7%
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.18%

7th percentile - higher than 7% of all known CVEs

Summary

In the Linux kernel, the dev_fill_forward_path() function contains a WARN_ON_ONCE that can be triggered by a routing loop in IPIP and IPv6 tunnels when the route to the tunnel's remote endpoint resolves back to the tunnel itself. This configuration is possible for users with CAP_NET_ADMIN and causes the function to make no progress, triggering the warning when a flowtable tries to offload a flow through the tunnel.

Risk Assessment

The warning may cause kernel log spam and potential performance issues, but it is not a direct security threat; however, it can mask real errors and hinder diagnostics.

Recommendation

Apply the Linux kernel patch that removes the WARN_ON_ONCE and simply fails the walk, treating the routing loop as a transmit error, similar to the earlier fix for path stack overflow.

Other vulnerabilities in Linux kernel

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Original NVD description (English source)

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.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS