On 2025-10-06, CISA added CVE-2021-43226 (Microsoft Windows) to its Known Exploited Vulnerabilities (KEV) catalog [2]. The vulnerability is listed in the catalog as "Microsoft Windows Privilege Escalation Vulnerability" [2]. CISA requires remediation in accordance with the listed vendor mitigation guidance; see the original text in the body for specific requirements [2].
Backfill: this event became public on Oct 6, 2025 and we added it on Nov 10, 2026. It is not a new event.
CISA Adds Microsoft Windows Vulnerability CVE-2021-43226 to Known Exploited Vulnerabilities Catalog
1 min read
- Disclosed
- Oct 6, 2025
- Published
- Nov 10, 2026
- Last updated
- Nov 8, 2026
- CVSS basis
- Our assessment
- 3.3%, higher than 89% of CVEs
- Exploitation and patch status
- ExploitedKEV
- Attack vector
- Vulnerability status
- Actor type
- Motivation
On this page
30-second summary
What happened
Who is affected
Industries mainly affected: Government, Cross-industry
What to do nowOur advice
CISA requires remediation in accordance with the listed vendor mitigation guidance; see the original text in the body for specific requirements [2].
Timeline
Technical details
CISA KEV Listing Record
CISA added CVE-2021-43226 (Microsoft Windows) to the Known Exploited Vulnerabilities () catalog on 2025-10-06 [2].
Original Technical 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. [2]
Official 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. [2]
Individual Vulnerability Record
The U.S. National Vulnerability Database (NVD) provides an independent vulnerability record and description for CVE-2021-43226 [1].
References
Official / primary3
- [1]
“Windows Common Log File System Driver Elevation of Privilege Vulnerability”
- [2]
This site aggregates public information and is not security consulting advice. Test remediation steps before applying.