CVE-2026-2636
Denial of Service in Microsoft OS
CVSS Score
5.5
EPSS Score
0.0%
EPSS Percentile
0th
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 |
| Vendor | microsoft |
| Product | windows os |
| Ecosystems | |
| Industries | TechnologyEnterprise |
| Published | Feb 25, 2026 |
| Last Updated | Feb 26, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High
Affected Versions
Microsoft / Windows OS
0 < 25H2 0 ≤ 1123h2