# CVE-2026-80996: net: l2tp: do not propagate multicast notification errors

> An attacker with local access can cause resource exhaustion in the Linux kernel L2TP module by triggering repeated operations that fail due to notification errors.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 11 Sep 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-100832, BELL-CVE-2026-80996, DEBIAN-CVE-2026-80996, GHSA-hc5w-42jx-9cr6, UBUNTU-CVE-2026-80996

## What is CVE-2026-80996?

CVE-2026-80996 is a denial of service vulnerability in Linux, published on 11 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

net: l2tp: do not propagate multicast notification errors

The tunnel create, tunnel modify, session create, and session modify
netlink handlers send multicast notifications through helpers that can fail
while allocating or encoding a message, or while multicasting it.

For tunnel and session create/modify, a notification is sent after the live
operation has completed. Returning a best-effort notification error as the
command result can therefore report failure for an operation that already
committed and can cause callers to retry and accumulate live objects.

Keep sending notifications for listener visibility, but do not propagate
their best-effort status as the command result. This also keeps the tunnel
modify command consistent with the other notification-only paths.

## Which versions are affected by CVE-2026-80996?


## How do I fix CVE-2026-80996?

Apply the vendor's patch.

## Is CVE-2026-80996 being exploited?

There is no known exploitation of CVE-2026-80996 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80996 and fix it if it is affected.

What it is: CVE-2026-80996 is a denial of service vulnerability in Linux, published on 11 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-80996 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-2026-80996/ (Markdown: https://insights.sbomify.com/CVE-2026-80996/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80996
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80996
- OSV: https://osv.dev/vulnerability/CVE-2026-80996

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80996/
Summaries are generated and may contain mistakes; the official description above is the record.