# CVE-2026-12855: H19WMIHandlerSmm: unvalidated memory boundary could result in arbitrary code execution.

> An unvalidated memory boundary in HP-specific InsydeH2O firmware allows arbitrary code execution, requiring firmware updates.

- **Severity:** High 8.2 (`CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 9 Sep 2026
- **Updated:** 1 Oct 2026
- **Also known as:** GHSA-w7c8-hp3q-qpv8

## What is CVE-2026-12855?

CVE-2026-12855 is a high-severity memory corruption vulnerability in InsydeH2O, published on 9 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Unvalidated memory boundary could result in arbitrary code execution. The vulnerability exists in the code developed specifically for HP projects.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2026-12855?


## How do I fix CVE-2026-12855?

No fix has been published for CVE-2026-12855 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-12855 being exploited?

There is no known exploitation of CVE-2026-12855 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-12855 and fix it if it is affected.

What it is: CVE-2026-12855 is a high-severity memory corruption vulnerability in InsydeH2O, published on 9 Sep 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-2026-12855 in the wild and no public exploit code.

Affected product: InsydeH2O. 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-2026-12855/ (Markdown: https://insights.sbomify.com/CVE-2026-12855/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-12855
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-12855
- OSV: https://osv.dev/vulnerability/CVE-2026-12855

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-12855/
Summaries are generated and may contain mistakes; the official description above is the record.