# CVE-2026-64285: KVM: SEV: Pin source page for write when adding CPUID data for SNP guest

> A missing write pin in KVM SEV SNP guest setup allows kernel writes to read-only memory, potentially causing memory corruption or privilege escalation.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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:** 25 Jul 2026
- **Updated:** 17 Aug 2026
- **Also known as:** DEBIAN-CVE-2026-64285, GHSA-9frv-wmxv-xpwj, ROOT-OS-UBUNTU-2204-CVE-2026-64285, UBUNTU-CVE-2026-64285

## What is CVE-2026-64285?

CVE-2026-64285 is a medium-severity memory corruption vulnerability in Linux kernel, published on 25 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: SEV: Pin source page for write when adding CPUID data for SNP guest

When populating a guest_memfd instance with the initial CPUID data for an
SNP guest, acquire a writable pin on the source page as KVM will write back
the "correct" CPUID information if the userspace provided data is rejected
by trusted firmware.  Because KVM writes to the source page using a kernel
mapping, pinning for read could result in KVM clobbering read-only memory.

Note, well-behaved VMMs are unlikely to be affected, as CPUID information
is almost always dynamically generated by userspace, i.e. it's unlikely for
the CPUID information to be backed by a read-only mapping.

[sean: rewrite shortlog and changelog, tag for stable@]

## Which versions are affected by CVE-2026-64285?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-64285?

Apply the vendor's patch.

## Is CVE-2026-64285 being exploited?

There is no known exploitation of CVE-2026-64285 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-2026-64285 and fix it if it is affected.

What it is: CVE-2026-64285 is a medium-severity memory corruption vulnerability in Linux kernel, published on 25 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-2026-64285 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-2026-64285/ (Markdown: https://insights.sbomify.com/CVE-2026-64285/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-64285
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-64285
- OSV: https://osv.dev/vulnerability/CVE-2026-64285

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-64285/
Summaries are generated and may contain mistakes; the official description above is the record.