# CVE-2026-80846: xfrm: drop ESP-in-TCP packets with no ingress device

> A null pointer dereference in the Linux kernel's XFRM subsystem allows remote attackers to cause a denial of service via crafted ESP-in-TCP packets.

- **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:** 4 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-99431, BELL-CVE-2026-80846, DEBIAN-CVE-2026-80846, GHSA-7qhp-m2hr-xxjv, UBUNTU-CVE-2026-80846

## What is CVE-2026-80846?

CVE-2026-80846 is a vulnerability in Linux, published on 4 Sep 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:

xfrm: drop ESP-in-TCP packets with no ingress device

ESP-in-TCP receives records through the TCP strparser. handle_esp()
restores skb->dev from the saved skb_iif before passing the packet into
the XFRM input path.

Queued TCP data can be processed after the original ingress device has
been removed, for example during veth or net namespace teardown. In that
case dev_get_by_index_rcu() returns NULL. The XFRM IPv4 and IPv6 input
paths both expect skb->dev to be valid while building the route lookup,
so queued ESP-in-TCP data can dereference a NULL device.

Drop the packet if the saved ingress device can no longer be resolved.
Such a packet can no longer be routed through the normal XFRM receive
path, and this preserves the existing behaviour for packets whose ingress
device still exists.

## Which versions are affected by CVE-2026-80846?


## How do I fix CVE-2026-80846?

Apply the vendor's patch.

## Is CVE-2026-80846 being exploited?

There is no known exploitation of CVE-2026-80846 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80846 and fix it if it is affected.

What it is: CVE-2026-80846 is a vulnerability in Linux, published on 4 Sep 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-2026-80846 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-2026-80846/ (Markdown: https://insights.sbomify.com/CVE-2026-80846/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80846
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80846
- OSV: https://osv.dev/vulnerability/CVE-2026-80846

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80846/
Summaries are generated and may contain mistakes; the official description above is the record.