# CVE-2026-80735: ovpn: ensure socket is owned by ovpn before deref sk_user_data

> A missing check in the Linux kernel OVPN module allows out-of-bounds reads when sockets are shared with other subsystems like BPF SOCKMAP.

- **Severity:** High 7.3 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L`)
- **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:** 3 Sep 2026
- **Updated:** 4 Sep 2026
- **Also known as:** BELL-CVE-2026-80735, DEBIAN-CVE-2026-80735, GHSA-2h35-47m3-h9hp, UBUNTU-CVE-2026-80735

## What is CVE-2026-80735?

CVE-2026-80735 is a high-severity memory corruption vulnerability in Linux, published on 3 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:

ovpn: ensure socket is owned by ovpn before deref sk_user_data

Some subsystems, like BPF SOCKMAP, set sk_user_data without
actually setting the encap_type.

For this reason, we must make sure that the type is the
one ovpn expects before dereferencing sk_user_data.

Failing to do so may lead to out-of-bounds reads.

## Which versions are affected by CVE-2026-80735?


## How do I fix CVE-2026-80735?

Apply the vendor's patch.

## Is CVE-2026-80735 being exploited?

There is no known exploitation of CVE-2026-80735 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80735 and fix it if it is affected.

What it is: CVE-2026-80735 is a high-severity memory corruption vulnerability in Linux, published on 3 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-2026-80735 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-2026-80735/ (Markdown: https://insights.sbomify.com/CVE-2026-80735/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80735
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80735
- OSV: https://osv.dev/vulnerability/CVE-2026-80735

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80735/
Summaries are generated and may contain mistakes; the official description above is the record.