CVE-2021-43226
KEVRansomware UseMicrosoft Windows Privilege Escalation Vulnerability
Description
Microsoft Windows Common Log File System Driver contains a privilege escalation vulnerability that could allow a local, privileged attacker to bypass certain security mechanisms.
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:HPublishedDec 15, 2021
Last modifiedAug 22, 2026
Added to KEVOct 6, 2025
Remediation dueOct 27, 2025
References
- portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-43226PatchVendor Advisory
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-43226US 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 364 days
- Ransomware
- Used in known ransomware campaigns
- CVSS
- 7.8 HIGH
- EPSS (30-day exploit probability)
- 3.3% · top 12% of all CVEs
- Weakness
- NVD-CWE-noinfo
Recommended actions
- 1.Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
- 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.