CVE-2026-2636 | THREATINT

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.

PUBLISHED Reserved 2026-02-17 | Published 2026-02-25 | Updated 2026-02-26 | Assigner Fortra

MEDIUM: 5.5CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Problem types

CWE-159 Improper Handling of Invalid Use of Special Elements

Product status

Default status

affected

Any version before 25H2

affected

Any version

affected

References

www.fortra.com/security/advisories/research/fr-2026-001

cve.org (CVE-2026-2636)

nvd.nist.gov (CVE-2026-2636)

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