# CVE-2026-64555: KVM: arm64: nv: Fix SPSR_EL2 restore in kvm_hyp_handle_mops()

> A missing state translation in KVM arm64 nested virtualization allows guest control over host registers, potentially enabling privilege escalation or code execution.

- **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:** 27 Jul 2026
- **Updated:** 17 Aug 2026
- **Also known as:** BELL-CVE-2026-64555, DEBIAN-CVE-2026-64555, GHSA-mh5j-7pgc-m97g, UBUNTU-CVE-2026-64555

## What is CVE-2026-64555?

CVE-2026-64555 is a high-severity vulnerability in Linux, published on 27 Jul 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: nv: Fix SPSR_EL2 restore in kvm_hyp_handle_mops()

kvm_hyp_handle_mops() resets the single-step state machine as part of
rewinding state for a MOPS exception by modifying vcpu_cpsr() and
writing the result directly into hardware.

In the case of nested virtualization, vcpu_cpsr() is a synthetic value
such that the rest of KVM can deal with vEL2 cleanly. That means the
value requires translation before being written into hardware, which is
unfortunately missing from the MOPS handler.

Fix it by directly modifying SPSR_EL2 and avoiding the synthetic state
altogether, which will be resynchronized on the next 'full' exit back
to KVM.

## Which versions are affected by CVE-2026-64555?


## How do I fix CVE-2026-64555?

Apply the vendor's patch.

## Is CVE-2026-64555 being exploited?

There is no known exploitation of CVE-2026-64555 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-64555 and fix it if it is affected.

What it is: CVE-2026-64555 is a high-severity vulnerability in Linux, published on 27 Jul 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-2026-64555 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-2026-64555/ (Markdown: https://insights.sbomify.com/CVE-2026-64555/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-64555
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-64555
- OSV: https://osv.dev/vulnerability/CVE-2026-64555

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-64555/
Summaries are generated and may contain mistakes; the official description above is the record.