CVE-2026-64410 netfilter: flowtable: IPIP tunnel hardware offload is not yet support
The Linux kernel fails to properly handle unsupported IPIP tunnel hardware offload, potentially causing resource exhaustion or instability when such configurations are attempted.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-64410?
CVE-2026-64410 is a critical denial of service vulnerability in Linux kernel, published on 25 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
netfilter: flowtable: IPIP tunnel hardware offload is not yet support
No driver supports for IPIP tunnels yet, give up early on setting up the hardware offload for this scenario.
This patch adds a stub that can be enhanced to add more configuration that are currently not supported. As of now, the offload work is enqueued to the worker, then ignored if the hardware offload configuration is not supported.
Check the NF_FLOW_HW flag to know if this entry was already tried once to be offloaded so this is not retried on refresh when unsupported. Move NF_FLOW_HW flag check to nf_flow_offload_add(). If this NF_FLOW_HW flag is unset the _del and _stats variants are never called.
This can be updated later on to skip hardware offload work to be queued in case hardware offload does not support it.
Which versions are affected by CVE-2026-64410?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-64410?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-64410 being exploited?
There is no known exploitation of CVE-2026-64410 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as DEBIAN-CVE-2026-64410, GHSA-grq9-9wcr-7jrj, ROOT-OS-UBUNTU-2204-CVE-2026-64410, UBUNTU-CVE-2026-64410.