CVE-2026-40400 - Windows PowerShell Remote Code Execution Vulnerability - is a relative path traversal issue affecting Windows PowerShell. Microsoft rates it as Remote Code Execution with a CVSS v3.1 base score of 8.0 (High) and temporal score of 7.0. The vector is NETWORK, attack complexity is LOW, privileges required are LOW, and user interaction is REQUIRED. Microsoft reports no public disclosure, no known exploitation, and exploit code maturity is UNPROVEN. Because user interaction is required and Microsoft rates exploitation as unlikely, the enterprise risk is lower than a no-interaction network RCE, but it is still a high-severity issue for environments where users may be induced to interact with attacker-controlled content.

Highlights:
- CVSS scores: Base 8.0 - Temporal 7.0
- Exploit status & code maturity: Publicly Disclosed: No; Exploited: No; Exploit Code Maturity: UNPROVEN.
- Impact: Remote Code Execution with HIGH confidentiality, integrity, and availability impact.
- Exploitation likelihood: Exploitation Unlikely; network vector with LOW attack complexity, LOW privileges required, and REQUIRED user interaction.
- Severity for enterprise: High severity. Network reachability raises exposure, but REQUIRED user interaction reduces practical risk compared with fully remote, no-interaction attacks.
- Patch status: available

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