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CVE-2026-2636

MEDIUM CVSS 3.1: 5.5 EPSS 0.05%
Updated Feb 25, 2026
Microsoft
Parameter Value
CVSS 5.5 (MEDIUM)
Type CWE-159
Vendor Microsoft
Public PoC No

This vulnerability is caused by a CWE‑159: "Improper Handling of Invalid Use of Special Elements" weakness, which leads to an unrecoverable inconsistency in the CLFS.sys driver. This condition forces a call to the KeBugCheckEx function, allowing an unprivileged user to trigger a system crash. Microsoft silently fixed this vulnerability in the September 2025 cumulative update for Windows 11 2024 LTSC and Windows Server 2025.

Windows 25H2 (released in September) was released with the patch. Windows 1123h2 and earlier versions remain vulnerable.

Attack Parameters

Attack Vector
Local
Requires local access
Attack Complexity
Low
Easy to exploit
Privileges Required
Low
Basic privileges needed
User Interaction
None
No user interaction needed

Impact Assessment

Confidentiality
None
No data leak
Integrity
None
No data modification
Availability
High
Complete denial of service

CVSS Vector v3.1

Weakness Type (CWE)