CVE-2026-98853 net: gso: limit recursive IP-in-IP segmentation
A remote attacker can cause a kernel stack exhaustion and denial of service by sending deeply nested IP-in-IP packets to the Linux kernel.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-98853?
CVE-2026-98853 is a denial of service vulnerability in Linux, published on 18 Oct 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:
net: gso: limit recursive IP-in-IP segmentation
IP-in-IP GSO can re-enter inet_gso_segment() or ipv6_gso_segment() for each nested IP header. encap_level tracks header bytes, not callback depth, so a deep chain can exhaust the kernel stack. Making inet_gso_segment() stackable introduced unbounded IPv4 nesting; IPIP GSO/TSO later made the path reachable. The IPv6 stackable path was introduced separately and uses the same guard.
Count IPv4 and IPv6 GSO handler entries in skb_gso_cb, initialized once per top-level GSO operation and preserved across GRE/UDP context changes. Use the existing IP_TUNNEL_RECURSION_LIMIT for both handlers. The first five entries pass, and the sixth returns -EINVAL before dispatching another GSO callback.
Which versions are affected by CVE-2026-98853?
How do I fix CVE-2026-98853?
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-2026-98853 being exploited?
There is no known exploitation of CVE-2026-98853 in the wild and no public exploit code.
Sources
Also known as AZL-108873, BELL-CVE-2026-98853, DEBIAN-CVE-2026-98853, GHSA-3hxr-fh6w-v89j, UBUNTU-CVE-2026-98853.