# CVE-2026-89967: mm/migrate_device: avoid out-of-bounds writes for compound folios

> An out-of-bounds write in the Linux kernel's device memory migration code allows attackers to potentially execute arbitrary code or escalate privileges.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/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:** 16 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-89967, GHSA-mmrq-wq59-jg48, UBUNTU-CVE-2026-89967

## What is CVE-2026-89967?

CVE-2026-89967 is a high-severity memory corruption vulnerability in Linux, published on 16 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:

mm/migrate_device: avoid out-of-bounds writes for compound folios

migrate_device_range() and migrate_device_pfns() clear the entries
following a compound folio so that the PFN arrays retain their
page-granular representation.

If a compound folio extends beyond the end of the caller-provided range,
the loops clear all following folio entries without limiting them to the
number of slots remaining in the npages-sized array, causing an
out-of-bounds write.

Do not proceed with a compound folio if its page-granular representation
does not fit entirely in the remaining PFN array.  If this happens, drop
any reference and lock acquired for the folio, clear the remaining
entries, and stop collecting.

Observed with a KASAN x86 QEMU kernel using the HMM migrate_anon_huge_zero
selftest.  Closing /dev/hmm_dmirror0 after migrating an anonymous huge
page to device memory exercises:

  dmirror_fops_release()
    -> dmirror_device_evict_chunk()
      -> migrate_device_range()

## Which versions are affected by CVE-2026-89967?


## How do I fix CVE-2026-89967?

Apply the vendor's patch.

## Is CVE-2026-89967 being exploited?

There is no known exploitation of CVE-2026-89967 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89967 and fix it if it is affected.

What it is: CVE-2026-89967 is a high-severity memory corruption vulnerability in Linux, published on 16 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-2026-89967 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-2026-89967/ (Markdown: https://insights.sbomify.com/CVE-2026-89967/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89967
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89967
- OSV: https://osv.dev/vulnerability/CVE-2026-89967

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89967/
Summaries are generated and may contain mistakes; the official description above is the record.