# CVE-2026-46317: KVM: arm64: Reassign nested_mmus array behind mmu_lock

> A use-after-free in the Linux kernel's KVM arm64 module allows attackers to potentially execute code or escalate privileges via race conditions in nested MMU handling.

- **Severity:** High 8.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/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:** 9 Jun 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-46317, DEBIAN-CVE-2026-46317, GHSA-5vrh-8j67-jvj4, ROOT-OS-DEBIAN-13-CVE-2026-46317, UBUNTU-CVE-2026-46317

## What is CVE-2026-46317?

CVE-2026-46317 is a high-severity use after free vulnerability in Linux kernel, published on 9 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:

KVM: arm64: Reassign nested_mmus array behind mmu_lock

kvm->arch.nested_mmus[] is walked under kvm->mmu_lock, including from the
MMU notifier path (kvm_unmap_gfn_range() -> kvm_nested_s2_unmap()), which
can run at any time. kvm_vcpu_init_nested() reallocates the array and frees
the old buffer while holding only kvm->arch.config_lock, so such a walker
can reference the freed array.

Allocate the new array outside of mmu_lock, as the allocation can sleep.
Under the lock, copy the existing entries, fix up the back pointers and
reassign the array. Free the old buffer after dropping the lock, as
kvfree() can sleep as well.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2026-46317?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-46317?

Apply the vendor's patch.

## Is CVE-2026-46317 being exploited?

There is no known exploitation of CVE-2026-46317 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-2026-46317 and fix it if it is affected.

What it is: CVE-2026-46317 is a high-severity use after free vulnerability in Linux kernel, published on 9 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-2026-46317 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-2026-46317/ (Markdown: https://insights.sbomify.com/CVE-2026-46317/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-46317
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-46317
- OSV: https://osv.dev/vulnerability/CVE-2026-46317

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-46317/
Summaries are generated and may contain mistakes; the official description above is the record.