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

Overview

Severity
High (CVSS 7.8)
CVSS Vector
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
Category
Elevation of Privilege
Exploit Status
Not Exploited
Exploitation Likelihood
More Likely
Patch Tuesday
2026-Aug
Released
2026-08-11
Last Updated
2026-08-27
EPSS Score
0.30% (percentile: 20.2%)

Description

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

FAQ

What privileges could be gained by an attacker who successfully exploited this vulnerability? An attacker who successfully exploited this vulnerability could gain SYSTEM privileges.

Detection & Weaponization (1 sources)

Maturity: Exploit

  • GitHub PoC: 4 repositories

Affected Products (9)

ESU

  • Windows 10 Version 22H2 for x64-based Systems
  • Windows 10 Version 22H2 for ARM64-based Systems
  • Windows 10 Version 22H2 for 32-bit Systems

Windows

  • Windows 11 Version 25H2 for ARM64-based Systems
  • Windows 11 Version 25H2 for x64-based Systems
  • Windows 11 Version 24H2 for ARM64-based Systems
  • Windows 11 Version 24H2 for x64-based Systems
  • Windows 11 version 26H1 for x64-based Systems
  • Windows 11 Version 26H1 for ARM64-based Systems

Security Updates (4)

Acknowledgments

James Forshaw with Google Project Zero, shoodagiri with <a href="https://gmo-cybersecurity.com/">GMO Cybersecurity by Ierae Inc</a>, <a href="https://www.linkedin.com/in/daniele-linguaglossa/">Daniele Linguaglossa</a>, <a href="https://infosec.exchange/@wdormann">Will Dormann</a> with <a href="https://vu.ls/">Vul Labs</a>, yhw &amp; txz, <a href="https://twitter.com/philiptsukerman">Philip Tsukerman</a> with Palo Alto Networks, Anonymous, <a href="https://github.com/rat5ak">Daniel Wade</a> with <a href="https://nadsec.online/">nadsec</a>, hamayanhamayan, <a href="https://www.linkedin.com/in/kim-d-5b3114111/">Kim Dvash</a>, kaijieguigui working with TrendAI Zero Day Initiative, <a href="https://www.linkedin.com/in/david-c-826599a4/">David Carliez</a> with DC CyberSecurity, <a href="https://x.com/thomasklemenc">Thomas Klemenc</a>, sorte, haowei yan

Revision History

  • 2026-08-11: Information published.
  • 2026-08-12: Updated an acknowledgement. This is an informational change only.
  • 2026-08-13: Acknowledgement Updated
  • 2026-08-14: Acknowledgement Updated
  • 2026-08-18: Acknowledgement Updated
  • 2026-08-27: Updated an acknowledgement. This is an informational change only.