CVE-2026-50477 is a Windows Kernel heap-based buffer overflow that can be used for elevation of privilege to SYSTEM. Microsoft rates it CVSS v3.1 8.8 high with vector AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H, indicating a local attack requiring low privileges and no user interaction, with changed scope and high confidentiality, integrity, and availability impact. Microsoft reports no public disclosure and no known exploitation, with exploit code maturity unproven. Because this is a local privilege escalation issue, enterprise risk is highest where attackers can already run code or obtain low-privilege access on affected Windows systems.

Highlights:
- CVSS scores: Base 8.8 - Temporal 7.7
- Exploit status & code maturity: Publicly Disclosed: No; Exploited: No; Exploit Code Maturity: UNPROVEN.
- Impact: Elevation of Privilege; confidentiality, integrity, and availability impacts are HIGH.
- Exploitation likelihood: Exploitation Less Likely; local vector with LOW attack complexity, LOW privileges required, and NO user interaction.
- Severity for enterprise: High severity, but primarily a local escalation risk rather than a remote exposure risk; higher concern on systems where attackers may gain initial foothold or untrusted local access.
- 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