CVE-2026-2636

medium Microsoft
CVSS v3 Base Score
5.5
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
EPSS Score
0.0%
Exploitation probability in 30 days
Top 87% most likely to be exploited
Attack Characteristics
Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Confidentiality
None
Integrity
None
Availability
High
Published: February 25, 2026 (78 days ago)
Last Modified: February 27, 2026
Vendor: Microsoft

Description

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.

CWE

CWE-159

References

🔗 www.fortra.com