# CVE-2026-80886: serial: msm: Disable DMA for kernel console UART

> A race condition in the Linux kernel MSM serial driver can cause an infinite loop during concurrent writes, leading to a denial of service.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 4 Sep 2026
- **Updated:** 4 Sep 2026
- **Also known as:** BELL-CVE-2026-80886, DEBIAN-CVE-2026-80886, GHSA-f3wr-g9f6-6vgf, UBUNTU-CVE-2026-80886

## What is CVE-2026-80886?

CVE-2026-80886 is a vulnerability in Linux, published on 4 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:

serial: msm: Disable DMA for kernel console UART

At the moment, concurrent writes from userspace and the kernel to the
console can trigger a race condition that results in an infinite loop of
the same messages printed over and over again. This is most likely to
happen during system startup or shutdown when the init system starts/stops
a large number of system services that interact with various kernel code.

When userspace writes to the TTY device, the driver initiates an
asynchronous DMA transfer and releases the port lock. At the same moment,
the kernel printk path might grab the port lock and re-configure the UART
controller for PIO, without waiting for the DMA operation to complete. It
seems like this collision results in zero progress being reported for the
DMA engine, so the same text is printed to the console over and over again.

For the kernel console, we want a reliable output path that will be
functional even during crashes etc. So rather than implementing complex
code to synchronize the kernel console write routines with the userspace
DMA write routines, simply disable DMA for the console UART instance.

Similar checks exist in many other serial drivers, e.g. 8250_port.c,
imx.c, sh-sci.c etc.

## Which versions are affected by CVE-2026-80886?


## How do I fix CVE-2026-80886?

Apply the vendor's patch.

## Is CVE-2026-80886 being exploited?

There is no known exploitation of CVE-2026-80886 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80886 and fix it if it is affected.

What it is: CVE-2026-80886 is a vulnerability in Linux, published on 4 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-2026-80886 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-2026-80886/ (Markdown: https://insights.sbomify.com/CVE-2026-80886/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80886
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80886
- OSV: https://osv.dev/vulnerability/CVE-2026-80886

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80886/
Summaries are generated and may contain mistakes; the official description above is the record.