Exploited· due 2025-10-27used in ransomware
CVE-2021-43226
Microsoft Windows
Microsoft Windows Common Log File System Driver contains a privilege escalation vulnerability that could allow a local, privileged attacker to bypass certain security mechanisms.
Exploitation status
- CISA has confirmed this is being exploited in the wild. That is an observation of real attacks, not a prediction.
- It is known to have been used in ransomware campaigns.
- US federal civilian agencies are required to remediate it by 2025-10-27. That deadline does not bind private companies, but it is a reasonable benchmark for how urgently CISA views it.
Required action
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
CISA’s wording, unedited.
Scoring
- CVSS
- Not yet scored
Dates
- Published
- 2025-10-06
- Added to KEV
- 2025-10-06
- Remediation due
- 2025-10-27
- Sources
- CISA KEV