# CVE-2026-98718: KVM: SEV: Do cache maintenance on the source VM *before* clearing SEV state

> A race condition in KVM SEV migration allows host memory corruption and data leakage due to improper cache flushing order.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 18 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-98718, DEBIAN-CVE-2026-98718, GHSA-8j5c-4j8r-8m5m, UBUNTU-CVE-2026-98718

## What is CVE-2026-98718?

CVE-2026-98718 is a vulnerability in Linux, published on 18 Oct 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: Do cache maintenance on the source VM *before* clearing SEV state

Explicitly flush caches after intra-host migration before clearing "SEV
active" on the source VM, as doing cache maintenance afterwards creates a
tiny window where memory reclaim could return memory to the host without
performing a cache flush, e.g. as pointed out by Sashiko:

  CPU1 in sev_migrate_from():
    src->active = false;

  CPU2 running concurrent unmap:
    Since active is false, the automatic cache flush in
    sev_guest_memory_reclaimed is skipped.
    The host frees and reallocates the page.

  CPU1 in sev_migrate_from():
    sev_writeback_caches(src_kvm);
    Executes a hardware cache flush (wbnoinvd), which writes the guest's old
    dirty ciphertext over the new page owner's data.

## Which versions are affected by CVE-2026-98718?


## How do I fix CVE-2026-98718?

Apply the vendor's patch.

## Is CVE-2026-98718 being exploited?

There is no known exploitation of CVE-2026-98718 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98718 and fix it if it is affected.

What it is: CVE-2026-98718 is a vulnerability in Linux, published on 18 Oct 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-2026-98718 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-2026-98718/ (Markdown: https://insights.sbomify.com/CVE-2026-98718/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98718
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98718
- OSV: https://osv.dev/vulnerability/CVE-2026-98718

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98718/
Summaries are generated and may contain mistakes; the official description above is the record.