# CVE-2026-98720: KVM: nVMX: Force MSR bitmap refresh if runtime eVMCS controls are modified

> A guest VM can read or write the host's Task Priority Register due to a missing MSR bitmap refresh, potentially leading to information disclosure or privilege escalation.

- **Severity:** Not scored
- **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:** 18 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-109266, BELL-CVE-2026-98720, DEBIAN-CVE-2026-98720, GHSA-6822-57w6-j97m, UBUNTU-CVE-2026-98720

## What is CVE-2026-98720?

CVE-2026-98720 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: nVMX: Force MSR bitmap refresh if runtime eVMCS controls are modified

Force a refresh of the vmcs02 MSR bitmap during nested VM-Enter if the
runtime eVMCS controls (pin, primary, secondary, etc.) are being updated.
If L1 isn't intercepting TPR writes, runs L2 with TPR virtualization, and
then runs the same L2 with TPR virtualization disabled, KVM will fail to
refresh msr_bitmap02 and leave TPR in passthrough mode even though TPR
virtualization is disabled.  I.e. failure to refresh the bitmap lets L2 (or
L1 by proxy) read and write L0's TPR.

## Which versions are affected by CVE-2026-98720?


## How do I fix CVE-2026-98720?

Apply the vendor's patch.

## Is CVE-2026-98720 being exploited?

There is no known exploitation of CVE-2026-98720 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98720 and fix it if it is affected.

What it is: CVE-2026-98720 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-2026-98720 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-2026-98720/ (Markdown: https://insights.sbomify.com/CVE-2026-98720/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98720
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98720
- OSV: https://osv.dev/vulnerability/CVE-2026-98720

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98720/
Summaries are generated and may contain mistakes; the official description above is the record.