Exploited vulnerability

CVE-2021-43226

TLP:CLEAR

Microsoft Windows Privilege Escalation Vulnerability

Microsoft Windows Common Log File System Driver contains a privilege escalation vulnerability that could allow a local, privileged attacker to bypass certain security mechanisms.

Facts

Vendor: Microsoft
Product: Windows
CVSS: 7.8
EPSS (probability of exploitation within 30 days): 3.3 %
On CISA's Known Exploited Vulnerabilities list since: 6 October 2025
First known exploitation: 6 October 2025
Used in ransomware campaigns (per CISA): Yes
CISA's deadline for US federal agencies: 27 October 2025
First seen by Risk Letters: 6 October 2025

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Data: NVD (public domain), CISA KEV, FIRST EPSS, MITRE ATT&CK, AlienVault OTX. NVD