CVE-2026-66804

Analyzed Analyzed - Analysis Complete

Improper Access Control in Windows Cross Device Service

Publication date: 2026-08-11

Last updated on: 2026-08-14

Assigner: Microsoft Corporation

Description

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

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published

2026-08-11

Last Modified

2026-08-14

Generated

2026-09-01

AI Q&A

2026-08-11

EPSS Evaluated

2026-08-30

NVD

CVE-2026-66804

EUVD

EUVD-2026-56595

Affected Vendors & Products

Vendor	Product	Version / Range
microsoft	windows_10_22h2	to 10.0.19045.7663 (exc)
microsoft	windows_10_22h2	to 10.0.19045.7663 (exc)
microsoft	windows_10_22h2	to 10.0.19045.7663 (exc)
microsoft	windows_11_24h2	to 10.0.26100.9106 (exc)
microsoft	windows_11_24h2	to 10.0.26100.9106 (exc)
microsoft	windows_11_26h1	to 10.0.28000.2704 (exc)
microsoft	windows_11_26h1	to 10.0.28000.2704 (exc)
microsoft	windows_11_25h2	to 10.0.26200.9106 (exc)
microsoft	windows_11_25h2	to 10.0.26200.9106 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-284	The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor.

Attack-Flow Graph

Executive Summary

Improper access control in Windows Cross Device Service allows an authorized attacker to elevate privileges locally. This means an attacker with some access can gain higher permissions than intended.

Detection Guidance

Detection requires checking for unauthorized privilege escalation attempts in Windows Cross Device Service. Monitor event logs for unusual activity in services.msc related to the Windows Cross Device Service. Check for unexpected changes in user permissions or service configurations.

Impact Analysis

An attacker could exploit this to gain elevated privileges on your system, potentially allowing them to install malicious software, access sensitive data, or perform unauthorized actions.

Compliance Impact

The vulnerability allows local privilege escalation due to improper access control in Windows Cross Device Service. This could potentially lead to unauthorized access to sensitive data or system functions, which may impact compliance with standards like GDPR or HIPAA if exploited.

Mitigation Strategies

Apply the latest security updates from Microsoft to patch the Windows Cross Device Service. Monitor Microsoft's update guide for official patches and follow their recommended mitigation steps.

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