# CVE-2026-80636: netfilter: conntrack: revert ct extension genid infrastructure

> A null pointer dereference in the Linux kernel netfilter conntrack subsystem allows remote attackers to cause a system crash.

- **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:** 28 Aug 2026
- **Updated:** 28 Aug 2026
- **Also known as:** BELL-CVE-2026-80636, DEBIAN-CVE-2026-80636, GHSA-xc67-x6qc-f6hf, UBUNTU-CVE-2026-80636

## What is CVE-2026-80636?

CVE-2026-80636 is a vulnerability in Linux, published on 28 Aug 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: conntrack: revert ct extension genid infrastructure

This infrastructure is not used anymore after moving ct timeout and
helper to use datapath refcount to track object use.

Revert commit c56716c69ce1 ("netfilter: extensions: introduce extension
genid count") this patch disables all ct extensions (leading to NULL)
for unconfirmed conntracks, when this is only targeted at ct helper and
ct timeout. There is also codebase that dereferences the ct extension
without checking for NULL which could lead to crash.

## Which versions are affected by CVE-2026-80636?


## How do I fix CVE-2026-80636?

Apply the vendor's patch.

## Is CVE-2026-80636 being exploited?

There is no known exploitation of CVE-2026-80636 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80636 and fix it if it is affected.

What it is: CVE-2026-80636 is a vulnerability in Linux, published on 28 Aug 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-2026-80636 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-2026-80636/ (Markdown: https://insights.sbomify.com/CVE-2026-80636/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80636
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80636
- OSV: https://osv.dev/vulnerability/CVE-2026-80636

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80636/
Summaries are generated and may contain mistakes; the official description above is the record.