CVE-2026-58601 is a Windows Virtual Hard Disk (VHD) Miniport Driver heap-based buffer overflow that can be used for elevation of privilege to SYSTEM. Microsoft rates it High severity with a CVSS v3.1 base score of 7.8 and temporal score of 6.8. The vector is LOCAL, with low attack complexity, low privileges required, no user interaction, and unchanged scope. Microsoft reports no public disclosure and no known exploitation, with exploit code maturity unproven. Because the attack is local rather than network-based, enterprise risk is mainly from systems where untrusted local code or users can run.

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, integrity, and availability impacts are all HIGH. Microsoft states successful exploitation could grant SYSTEM privileges.
- Exploitation likelihood: Exploitation Less Likely; local vector, LOW attack complexity, LOW privileges required, and NO user interaction.
- Severity for enterprise: High technical severity, but lower exposure than remote vulnerabilities because the attack is LOCAL. Higher concern on endpoints, servers, or multi-user systems where attackers may obtain local execution.
- Patch status: available; customer action required

Affected systems:
- Windows 10 1607
- Windows 10 1809
- Windows 10 21H2
- Windows 10 22H2
- Windows 11 23H2
- Windows 11 24H2
- Windows 11 25H2
- Windows 11 26H1
- Windows 11 unspecified
- Windows Server 2016
- Windows Server 2019
- Windows Server 2022
- Windows Server 2025