CVE-2021-36955
KEVRansomware UseMicrosoft Windows Common Log File System (CLFS) Driver Privilege Escalation Vulnerability
Description
Microsoft Windows Common Log File System (CLFS) driver contains an unspecified vulnerability that allows for privilege escalation.
Windows Common Log File System Driver Elevation of Privilege Vulnerability
CVSS 3.1 vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HPublishedSep 15, 2021
Last modifiedAug 10, 2026
Added to KEVNov 3, 2021
Remediation dueNov 17, 2021
References
- msrc.microsoft.com/update-guide/vulnerability/CVE-2021-36955PatchVendor Advisory
- portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-36955PatchVendor Advisory
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-36955US Government Resource
0 recent articles mention this CVE
79
Risk assessment · High
Actively exploited and used by ransomware crews. Patch immediately.
- Exploitation
- Confirmed in the wild (CISA KEV)
- Federal remediation deadline
- Overdue by 1806 days
- Ransomware
- Used in known ransomware campaigns
- CVSS
- 7.8 HIGH
- EPSS (30-day exploit probability)
- 4.1% · top 9% of all CVEs
- Weakness
- NVD-CWE-noinfo
Recommended actions
- 1.Apply updates per vendor instructions.
- 2.Treat as emergency change: patch or isolate internet-facing instances first.
- 3.Hunt for compromise: review logs for the disclosure window, not just from the patch date.
- 4.Verify offline/immutable backups and segment the affected systems. This flaw is used for ransomware initial access.
Assessment is derived automatically from the live signals above; verify against your own asset inventory.