# CVE-2026-72287: KVM: nVMX: Move vTPR vs. TPR Threshold consistency check into "normal" checks

> A flaw in KVM's nested virtualization allows a guest to control CR3, potentially leading to privilege escalation or code execution in the host.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:H/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:** 15 Aug 2026
- **Updated:** 17 Aug 2026
- **Also known as:** DEBIAN-CVE-2026-72287, GHSA-2q48-vx2q-99r7, UBUNTU-CVE-2026-72287

## What is CVE-2026-72287?

CVE-2026-72287 is a high-severity vulnerability in Linux, published on 15 Aug 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: Move vTPR vs. TPR Threshold consistency check into "normal" checks

Move the off-by-default consistency check for vmcs12.tpr_threshold vs.
the virtual APIC vTPR into the "normal" controls checks, as waiting until
KVM has loaded some amount of state is unnecessary and actively dangerous.
Specifically, failure to unwind vmcs01.GUEST_CR3 to KVM's value when EPT
is disabled results in KVM running L1 with an L1-controlled CR3, not with
KVM's CR3!

Alternatively, KVM could simply reset the MMU to force a reload of
vmcs01.GUEST_CR3, but the _only_ reason the check was shoved into a "late"
flow was to wait until the vmcs12 pages were retrieved.  Rather than build
up more crusty code, simply access vTPR using a regular guest memory access
(performance isn't a concern).  To circumvent the restrictions that led to
KVM deferring nested_get_vmcs12_pages(), (a) use a VM-scoped API to read
guest memory so that it always hits non-SMM memslots (for RSM), and (b)
skip the check (since its off-by-default anyways) when the vCPU doesn't
want to run, i.e. when userspace is restoring/stuffing state.

If reading guest memory fails, simply skip the consistency check, as KVM's
de facto ABI is that VMX instruction accesses to non-existent memory get
PCI Bus Error semantics, where reads return 0xFFs.  And if vTPR=0xFF, then
the vTPR is guaranteed to be greater than or equal to TPR_THRESHOLD.

## Which versions are affected by CVE-2026-72287?


## How do I fix CVE-2026-72287?

Apply the vendor's patch.

## Is CVE-2026-72287 being exploited?

There is no known exploitation of CVE-2026-72287 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-72287 and fix it if it is affected.

What it is: CVE-2026-72287 is a high-severity vulnerability in Linux, published on 15 Aug 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-2026-72287 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-2026-72287/ (Markdown: https://insights.sbomify.com/CVE-2026-72287/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-72287
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-72287
- OSV: https://osv.dev/vulnerability/CVE-2026-72287

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-72287/
Summaries are generated and may contain mistakes; the official description above is the record.