# CVE-2026-46280: lib: test_hmm: evict device pages on file close to avoid use-after-free

> A use-after-free in the Linux kernel HMM selftests allows a local attacker to cause a kernel panic via a coredump, requiring a patch to fix.

- **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:** 8 Jun 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-89607, BELL-CVE-2026-46280, DEBIAN-CVE-2026-46280, GHSA-vjjg-r28q-g2g4, ROOT-OS-DEBIAN-11-CVE-2026-46280, ROOT-OS-DEBIAN-12-CVE-2026-46280, UBUNTU-CVE-2026-46280

## What is CVE-2026-46280?

CVE-2026-46280 is a high-severity use after free vulnerability in Linux kernel, published on 8 Jun 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:

lib: test_hmm: evict device pages on file close to avoid use-after-free

Patch series "Minor hmm_test fixes and cleanups".

Two bugfixes a cleanup for the HMM kernel selftests.  These were mostly
reported by Zenghui Yu with special thanks to Lorenzo for analysing and
pointing out the problems.

This patch (of 3):

When dmirror_fops_release() is called it frees the dmirror struct but
doesn't migrate device private pages back to system memory first.  This
leaves those pages with a dangling zone_device_data pointer to the freed
dmirror.

If a subsequent fault occurs on those pages (eg.  during coredump) the
dmirror_devmem_fault() callback dereferences the stale pointer causing a
kernel panic.  This was reported [1] when running mm/ksft_hmm.sh on arm64,
where a test failure triggered SIGABRT and the resulting coredump walked
the VMAs faulting in the stale device private pages.

Fix this by calling dmirror_device_evict_chunk() for each devmem chunk in
dmirror_fops_release() to migrate all device private pages back to system
memory before freeing the dmirror struct.  The function is moved earlier
in the file to avoid a forward declaration.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2026-46280?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-46280?

Apply the vendor's patch.

## Is CVE-2026-46280 being exploited?

There is no known exploitation of CVE-2026-46280 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-46280 and fix it if it is affected.

What it is: CVE-2026-46280 is a high-severity use after free vulnerability in Linux kernel, published on 8 Jun 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-2026-46280 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2026-46280/ (Markdown: https://insights.sbomify.com/CVE-2026-46280/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-46280
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-46280
- OSV: https://osv.dev/vulnerability/CVE-2026-46280

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-46280/
Summaries are generated and may contain mistakes; the official description above is the record.