# CVE-2026-66804: Microsoft Windows Cross Device Service Elevation of Privilege Vulnerability

> An authorized local attacker can elevate privileges due to improper access control in the Windows Cross Device Service.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C`)
- **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:** No
- **Published:** 11 Aug 2026
- **Updated:** 21 Oct 2026
- **Also known as:** GHSA-m9fr-m5pc-g6ww

## What is CVE-2026-66804?

CVE-2026-66804 is a high-severity vulnerability in Microsoft Windows 10 22h2, published on 11 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Improper access control in Windows Cross Device Service allows an authorized attacker to elevate privileges locally.

Weakness: CWE-284 (Improper Access Control)

## Which versions are affected by CVE-2026-66804?

It affects 4 products.


Products: Microsoft Windows 10 22h2, Microsoft Windows 11 24h2, Microsoft Windows 11 25h2, Microsoft Windows 11 26h1.

## How do I fix CVE-2026-66804?

No fix has been published for CVE-2026-66804 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-66804 being exploited?

There is no known exploitation of CVE-2026-66804 in the wild and no public exploit code.

Public exploit code:

- CVE-2026-66804 Windows Cross Device virtual camera EoP - Standard user to SYSTEM (github_poc): https://github.com/Rat5ak/CVE-2026-66804-CrossDevice-Service-EoP
- https://github.com/DavidCarliez/CVE-2026-66804-CrossDevice-LPE (github_poc): https://github.com/DavidCarliez/CVE-2026-66804-CrossDevice-LPE
- sadsadsa (github_poc): https://github.com/ZeroDayVPN/CVE-2026-66804-CrossDevice-Service-EoP
- https://github.com/CypherHippie/CVE-2026-66804 (github_poc): https://github.com/CypherHippie/CVE-2026-66804

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-66804 and fix it if it is affected.

What it is: CVE-2026-66804 is a high-severity vulnerability in Microsoft Windows 10 22h2, published on 11 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-2026-66804 in the wild and no public exploit code.

Affected product: Microsoft Windows 10 22h2. 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-2026-66804/ (Markdown: https://insights.sbomify.com/CVE-2026-66804/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-66804
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-66804
- OSV: https://osv.dev/vulnerability/CVE-2026-66804

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-66804/
Summaries are generated and may contain mistakes; the official description above is the record.