# CVE-2025-68191: udp_tunnel: use netdev_warn() instead of netdev_WARN()

> A flaw in the Linux kernel UDP tunnel module causes unnecessary kernel warnings on allocation failures, potentially leading to log spam or system instability.

- **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:** 16 Dec 2025
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2025-68191, DEBIAN-CVE-2025-68191, GHSA-wpgr-4vvj-xp76, ROOT-OS-DEBIAN-12-CVE-2025-68191, ROOT-OS-DEBIAN-13-CVE-2025-68191, ROOT-OS-UBUNTU-2204-CVE-2025-68191, ROOT-OS-UBUNTU-2404-CVE-2025-68191, UBUNTU-CVE-2025-68191

## What is CVE-2025-68191?

CVE-2025-68191 is a denial of service vulnerability in Linux, published on 16 Dec 2025. 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:

udp_tunnel: use netdev_warn() instead of netdev_WARN()

netdev_WARN() uses WARN/WARN_ON to print a backtrace along with
file and line information. In this case, udp_tunnel_nic_register()
returning an error is just a failed operation, not a kernel bug.

udp_tunnel_nic_register() can fail due to a memory allocation
failure (kzalloc() or udp_tunnel_nic_alloc()).
This is a normal runtime error and not a kernel bug.

Replace netdev_WARN() with netdev_warn() accordingly.

## Which versions are affected by CVE-2025-68191?


## How do I fix CVE-2025-68191?

Apply the vendor's patch.

## Is CVE-2025-68191 being exploited?

There is no known exploitation of CVE-2025-68191 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-68191 and fix it if it is affected.

What it is: CVE-2025-68191 is a denial of service vulnerability in Linux, published on 16 Dec 2025. 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-2025-68191 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-2025-68191/ (Markdown: https://insights.sbomify.com/CVE-2025-68191/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-68191
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-68191
- OSV: https://osv.dev/vulnerability/CVE-2025-68191

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-68191/
Summaries are generated and may contain mistakes; the official description above is the record.