Microsoft Windows Common Log File System (CLFS) Driver Privilege Escalation Vulnerability

HIGH 7.8EXPLOITED (CISA KEV)CVE-2021-36955 · Published 15/09/2021 · updated 10/08/2026

Microsoft Windows Common Log File System (CLFS) Driver Privilege Escalation Vulnerability. Actively exploited: CISA added this vulnerability to its Known Exploited Vulnerabilities catalog on 03/11/2021. Patch affected systems as an emergency. It is known to be used in ransomware campaigns.

Package	Affected versions	Patched versions
Windows Microsoft	Versions not published yet (product named by CISA KEV)

Description

Windows Common Log File System Driver Elevation of Privilege Vulnerability

References

msrc.microsoft.com/update-guide/vulnerability/CVE-2021-36955 · Patch
portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-36955 · Patch
cisa.gov/known-exploited-vulnerabilities-catalog · US Government Resource
CISA KEV · CVE-2021-36955

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