# CVE-2026-72239: x86/virt/sev: Revert "Drop WBINVD before setting MSR_AMD64_SYSCFG_SNP_EN"

> A race condition in Linux kernel SEV initialization may leave dirty cache lines unflushed, violating AMD SNP firmware requirements.

- **Severity:** Critical 9.3 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **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-2026-72239, GHSA-mh7r-v762-68jw, UBUNTU-CVE-2026-72239

## What is CVE-2026-72239?

CVE-2026-72239 is a critical 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:

x86/virt/sev: Revert "Drop WBINVD before setting MSR_AMD64_SYSCFG_SNP_EN"

Revert

  99cf1fb58e68 ("x86/virt/sev: Drop WBINVD before setting MSR_AMD64_SYSCFG_SNP_EN").

Section 8.8 of the SNP spec says:

  Before invoking SNP_INIT_EX with INIT_RMP set to 1, software must ensure
  that no CPUs contain dirty cache lines for the memory containing the RMP.

Cachelines can be moved from cache to cache in a dirty state. The
wbinvd_on_all_cpus() before SNP_INIT_EX flushes the caches for each CPU, but
if the IPIs for WBINVD race with this dirty cacheline movement, it is possible
that they may not get flushed, violating the firmware requirement.

Doing wbinvd_on_all_cpus() before setting SNPEn is safer since the RMP
table is not yet in use.

  [ Heroically bisected by Srikanth. ]
  [ bp: Massage commit message. ]

## Which versions are affected by CVE-2026-72239?


## How do I fix CVE-2026-72239?

Apply the vendor's patch.

## Is CVE-2026-72239 being exploited?

There is no known exploitation of CVE-2026-72239 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-72239 and fix it if it is affected.

What it is: CVE-2026-72239 is a critical 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-2026-72239 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-2026-72239/ (Markdown: https://insights.sbomify.com/CVE-2026-72239/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-72239
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-72239
- OSV: https://osv.dev/vulnerability/CVE-2026-72239

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-72239/
Summaries are generated and may contain mistakes; the official description above is the record.