CVE-2026-50421 is a Windows Connected User Experiences and Telemetry elevation of privilege vulnerability caused by type confusion. Microsoft rates it as HIGH severity with a CVSS v3.1 base score of 7.8 and temporal score of 6.8. The attack vector is LOCAL, with LOW attack complexity, LOW privileges required, and no user interaction. If successfully exploited, an attacker could gain SYSTEM privileges. Microsoft reports no public disclosure and no known exploitation, and exploit code maturity is UNPROVEN; the latest software release indicates exploitation is unlikely. Because this is a local privilege escalation, enterprise risk is primarily to systems where an attacker already has local access or can run code on the host.

Highlights:
- CVSS scores: Base 7.8 - Temporal 6.8
- Exploit status & code maturity: Publicly Disclosed: No; Exploited: No; Exploit Code Maturity: UNPROVEN.
- Impact: Elevation of Privilege; confidentiality HIGH, integrity HIGH, availability HIGH.
- Exploitation likelihood: Exploitation Unlikely; LOCAL vector with LOW attack complexity, LOW privileges required, and no user interaction.
- Severity for enterprise: High technical severity, but lower exposure than network-reachable issues because exploitation requires local access; strongest risk is on endpoints or servers where an attacker can already execute local code.
- Patch status: available; customer action required.

Affected systems:
- Windows 10 1607
- Windows 10 1809
- Windows 10 21H2
- Windows 10 22H2
- Windows 11 24H2
- Windows 11 25H2
- Windows 11 26H1
- Windows 11 unspecified
- Windows Server 2016
- Windows Server 2019
- Windows Server 2022
- Windows Server 2025