# 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.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 18 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-108873, BELL-CVE-2026-98853, DEBIAN-CVE-2026-98853, GHSA-3hxr-fh6w-v89j, UBUNTU-CVE-2026-98853

## 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.

## Is CVE-2026-98853 being exploited?

There is no known exploitation of CVE-2026-98853 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98853 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-98853 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-98853/ (Markdown: https://insights.sbomify.com/CVE-2026-98853/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98853
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98853
- OSV: https://osv.dev/vulnerability/CVE-2026-98853

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98853/
Summaries are generated and may contain mistakes; the official description above is the record.