# CVE-2026-68142: geneve: require CAP_NET_ADMIN in the device netns for changelink

> Attackers with limited network namespace privileges can modify Geneve tunnel configurations in other namespaces, bypassing authorization checks.

- **Severity:** High 8.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H`)
- **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:** 10 Aug 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-68142, DEBIAN-CVE-2026-68142, GHSA-2rrg-cg9g-pgvw, UBUNTU-CVE-2026-68142

## What is CVE-2026-68142?

CVE-2026-68142 is a high-severity missing authorization vulnerability in Linux, published on 10 Aug 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:

geneve: require CAP_NET_ADMIN in the device netns for changelink

A tunnel changelink() operates on at most two netns, dev_net(dev) and
the sticky underlay netns geneve->net. They differ once the device is
created in or moved to a netns other than the one the request runs in.
The rtnl changelink path checks CAP_NET_ADMIN only against dev_net(dev),
so a caller privileged there but not in geneve->net can rewrite a geneve
device whose underlay lives in geneve->net.

geneve_changelink() applies the new configuration against geneve->net:
geneve_link_config() and the geneve_quiesce()/geneve_unquiesce() pair
reopen the underlay sockets in that netns (geneve_sock_add() uses
geneve->net), so the same reasoning as the tunnel changelink series
applies here.

Gate geneve_changelink() with rtnl_dev_link_net_capable(), at the top of
the op before any attribute is parsed, matching ipgre_changelink() and
the rest of the "require CAP_NET_ADMIN in the device netns for
changelink" series.

Found by 0sec automated security-research tooling (https://0sec.ai).

Weakness: CWE-862 (Missing Authorization)

## Which versions are affected by CVE-2026-68142?


## How do I fix CVE-2026-68142?

Apply the vendor's patch.

## Is CVE-2026-68142 being exploited?

There is no known exploitation of CVE-2026-68142 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-68142 and fix it if it is affected.

What it is: CVE-2026-68142 is a high-severity missing authorization vulnerability in Linux, published on 10 Aug 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-2026-68142 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-2026-68142/ (Markdown: https://insights.sbomify.com/CVE-2026-68142/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-68142
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-68142
- OSV: https://osv.dev/vulnerability/CVE-2026-68142

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-68142/
Summaries are generated and may contain mistakes; the official description above is the record.