Microsoft Windows Privilege Escalation Vulnerability
Release Date: 06th of October 2025
Impact : HIGH / CRITICAL
TLP Rating: Clear 
CERT Vanuatu (CERTVU) and the Department of Communication and Digital Transformation (DCDT) provide the following advisory.
This alert is relevant to Organizations and individuals that utilize the above products. This alert is intended to be understood by technical users and systems administrators.
What is it?
CVE-2021-43226 is an Elevation of Privileged (EoP) vulnerability in the Windows Common Log File System (CLFS) driver that can allow a local attacker to gain higher privileges on a vulnerable system.
What are the Systems affected?
Affected:
It affects multiple Windows client and server releases (Microsoft listed this as a Windows CLFS driver vulnerability disclosed in December 2021 and addressed as part of Microsoft December 2021(See Below Link)
What this means?
An attacker must already have some level of access to run code or commands on the target. By Exploiting the CLFS driver flaw, the attacker can escalate privileges to a higher level (e.g., SYSTEM), enabling further actions on the host.
Mitigation process
CERTVU recommend:
Apply Microsoft patching updates.
Also monitor for and suspicious local privilege escalation activities.
References
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog
- https://www.cve.org/CVERecord?id=CVE-2021-43226
- https://isc.sans.edu/diary/28132
- Download advisory (English): Microsoft Windows Privilege Escalation Vulnerability
- Download advisory (French): Vulnérabilité d'élévation de privilèges dans Microsoft Windows