# CVE-2026-80686: mm: migrate_device: fix pte_pfn/pte_dirty called on non-present PTE

> A local attacker can trigger a kernel crash or incorrect memory accounting by exploiting undefined behavior in device memory migration code.

- **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:** 28 Aug 2026
- **Updated:** 28 Aug 2026
- **Also known as:** AZL-98147, BELL-CVE-2026-80686, DEBIAN-CVE-2026-80686, GHSA-m9fp-2x7c-5r66, UBUNTU-CVE-2026-80686

## What is CVE-2026-80686?

CVE-2026-80686 is a vulnerability in Linux, published on 28 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:

mm: migrate_device: fix pte_pfn/pte_dirty called on non-present PTE

pte_pfn() and pte_dirty() have undefined behaviour when called on a
non-present PTE. In migrate_vma_collect_pmd(), these functions may be
invoked on non-present entries (e.g., device-private entries), leading
to potential crashes from pte_pfn() or incorrect dirty folio accounting
from pte_dirty(). Fix both by guarding with pte_present() checks.

## Which versions are affected by CVE-2026-80686?


## How do I fix CVE-2026-80686?

Apply the vendor's patch.

## Is CVE-2026-80686 being exploited?

There is no known exploitation of CVE-2026-80686 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80686 and fix it if it is affected.

What it is: CVE-2026-80686 is a vulnerability in Linux, published on 28 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-2026-80686 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-2026-80686/ (Markdown: https://insights.sbomify.com/CVE-2026-80686/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80686
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80686
- OSV: https://osv.dev/vulnerability/CVE-2026-80686

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80686/
Summaries are generated and may contain mistakes; the official description above is the record.