CVE-2026-56190 is a Remote Desktop Protocol (RDP) remote code execution vulnerability caused by use of an uninitialized resource. It has a CVSS v3.1 base score of 9.8 (Critical) and a temporal score of 8.5. The vector is network-based, requires no privileges and no user interaction, and has low attack complexity. Microsoft reports no public disclosure and no known exploitation, with exploit code maturity listed as UNPROVEN. The FAQ states the issue can be triggered by specially crafted RDP traffic against systems with Network Level Authentication (NLA) disabled. This is a high enterprise risk for exposed RDP services because exploitation can be attempted remotely without authentication or user interaction.

Highlights:
- CVSS scores: Base 9.8 - Temporal 8.5
- Exploit status & code maturity: Publicly Disclosed: No; Exploited: No; Exploit Code Maturity: UNPROVEN
- Impact: Remote Code Execution with HIGH confidentiality, integrity, and availability impacts
- Exploitation likelihood: Exploitation Less Likely; however, the attack vector is NETWORK with LOW attack complexity, NONE privileges, and NONE user interaction
- Severity for enterprise: Critical for network-exposed RDP services, especially where NLA is disabled; lower exposure for systems not reachable over RDP
- 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 2012
- Windows Server 2012 R2
- Windows Server 2016
- Windows Server 2019
- Windows Server 2022
- Windows Server 2025