CVE-2026-2636 MEDIUM

CVE-2026-2636: Denial of Service in Microsoft OS

Vendor Microsoft
Product Windows OS
Weakness CWE-159
Published February 25, 2026
Last update February 26, 2026
View on NVD All CVEs

CVSS base score

5.5/10
Attack vector Local
Attack complexity Low
Privileges required Low
User interaction None
Confidentiality None
Integrity None

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

February 25, 2026 CVE published
February 26, 2026 Record updated