CVE-2025-62458
win32k.sys -- elevation of privilege in Win32 Kernel Subsystem
Summary
| Field | Value |
|---|---|
| Driver | win32k.sys |
| Vulnerability Class | Elevation of Privilege |
| CVSS | 7.8 |
| Exploited ITW | No |
| Patch Date | December 9, 2025 |
Context
CVE-2025-62458 adds to the long list of Win32k privilege escalation vulnerabilities in this corpus. The Win32k subsystem is covered in detail in the Win32k Deep Dive, which documents 12 CVEs spanning type confusion, use-after-free, race conditions, and object lifetime errors. This CVE was patched in December 2025 without public exploitation, but the Win32k surface has a strong track record of ITW abuse: CVE-2022-21882, CVE-2023-29336, and CVE-2025-24983 were all exploited as zero-days.
Root Cause
Microsoft's advisory confirms an elevation of privilege in the Win32 Kernel Subsystem without disclosing the specific mechanism. The Win32k attack surface encompasses window object management, GDI operations, menu handling, and message dispatch. All of these involve complex object lifetimes and user-mode callback reentrancy, which are the root causes behind most Win32k CVEs. The driver's legacy architecture, dating back to Windows NT, means these patterns are deeply embedded.
Exploitation
An attacker at any interactive session can reach Win32k system calls without elevated privileges. The typical exploitation flow for a Win32k EoP involves creating specific window or GDI object configurations, triggering the vulnerable code path through a system call or callback sequence, then reclaiming freed or corrupted memory with controlled data to build a kernel R/W primitive. From there, token manipulation yields SYSTEM.
Exploitation Primitive
Crafted Win32k syscall --> kernel vulnerability --> SYSTEM
Broader Significance
Win32k vulnerabilities are significant not because any single CVE is novel, but because they keep appearing despite years of targeted mitigation work. Microsoft has shipped Win32k Type Isolation, syscall lockdown policies, and incremental callback hardening. The continued flow of CVEs suggests the architectural debt in win32k is too deep for incremental fixes to fully resolve.