CVE-2026-66802

This vulnerability is a flaw in how Windows’ device attestation services handle certain actions at the same time. If an attacker can reach the relevant network service, the timing mistake can let them run their own code on the affected Windows machine—like taking control of a door by exploiting a construction error in how the lock is managed.

This matters to you if you run Windows 10, Windows 11, or Windows Server 2019/2022/2025 systems that use Windows Device Health Attestation (DHA) / Attestation service components. It’s most relevant when the attestation functionality is reachable over a network path an attacker can use. If your DHA/Attestation usage is off or not network-accessible from untrusted sources, the risk is lower.

Treat this as urgent (RED) because it’s a remote code execution issue in Windows’ device attestation path, which means a network attacker can potentially gain control of a vulnerable system. The report is new and prompted a patch, and security attention indicates sophisticated threat activity may be involved.