CVE-2021-43226
Windows Common Log File System Driver Elevation of Privilege Vulnerability
do firstApply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Can a WAF block it? No. The attack needs local access to the machine, so a WAF is not on its path.
Also consider: patch
Based on the attack vector (local or physical access). We check Cloudflare, AWS, Google Cloud Armor and Azure; for Akamai, Imperva, Fastly, F5, ask your vendor.
Is CVE-2021-43226 being exploited?
Yes. CVE-2021-43226 appears in CISA's Known Exploited Vulnerabilities catalog, which means exploitation in the wild has been confirmed and reported. Treat it as active rather than theoretical, and patch it ahead of higher-scoring vulnerabilities that carry no exploitation evidence.
How severe is CVE-2021-43226?
CVE-2021-43226 is rated High with a CVSS score of 7.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2021-43226?
Yes. A fix has been recorded for CVE-2021-43226. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2021-43226 affect?
CVE-2021-43226 affects microsoft:windows_10_1507, microsoft:windows_10_1607, microsoft:windows_10_1809, microsoft:windows_10_1909, and 15 further products or versions. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
- affected>= 10.0.0 and < 10.0.10240.19145
- affected>= 10.0.0 and < 10.0.14393.4825
- affected>= 10.0.0 and < 10.0.17763.2366
- affected>= 10.0.0 and < 10.0.18363.1977
- affected>= 10.0.0 and < 10.0.19041.1415
- affected>= 10.0.0 and < 10.0.19042.1415
- affected>= 10.0.0 and < 10.0.19043.1415
- affected>= 10.0.0 and < 10.0.19044.1415
- affected>= 10.0.0 and < 10.0.22000.376
- affected>= 6.1.0 and < 6.1.7601.25796
- affected>= 6.1.0 and < 6.1.7601.25796
- affected>= 6.3.0 and < 6.3.9600.20207
- affected>= 6.1.0 and < 6.1.7601.25796
- affected>= 6.0.0 and < 6.1.7601.25796
- affected>= 6.0.0 and < 6.0.6003.21309
- affected>= 6.0.0 and < 6.0.6003.21309
- affected>= 6.0.0 and < 6.0.6003.21309
- affected>= 6.2.0 and < 6.2.9200.23545
- affected>= 6.2.0 and < 6.2.9200.23540
- affected>= 6.3.0 and < 6.3.9600.20207
- affected>= 6.3.0 and < 6.3.9600.20207
- affected>= 6.2.0 and < 6.2.9200.23545
- affected>= 6.2.0 and < 6.2.9200.23540
- affected>= 10.0.0 and < 10.0.14393.4825
- affected>= 10.0.0 and < 10.0.14393.4825
- affected>= 10.0.0 and < 10.0.17763.2366
- affected>= 10.0.0 and < 10.0.17763.2366
- affected>= 10.0.0 and < 10.0.20348.405
- affected>= 10.0.0 and < 10.0.19041.1415
- affected>= 10.0.0 and < 10.0.19042.1415
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.
public exploits
Unvetted proof-of-concept code on GitHub: 1 GitHub proof of concept
Listed so you can judge urgency, not as a recommendation to run anything. GitHub “proofs of concept” are unvetted: some are fake or carry malware. Exploit-DB marks the entries its staff verified.
cisa ssvc
- exploitation
- active
- automatable
- no
- technical impact
- total
Assessed by CISA 16 Dec 2021 (SSVC 2.0.3).
timeline
- 15 Dec 2021Published
- 16 Dec 2021CISA SSVC assessment: exploitation active · same day later
- 30 Oct 2023First proof-of-concept repository on GitHub (unvetted) · 683 days (about 2 years) later
- 6 Oct 2025Added to CISA KEV (exploited in the wild) · 707 days (about 2 years) later
- 27 Oct 2025CISA remediation due date (US federal agencies) · 21 days later
- 22 Aug 2026CVE record last updated · 299 days (about 10 months) later
- 2 Nov 2026Analysed by vulneraibility.com · 73 days (about 2 months) later
- Linkportal.msrc.microsoft.com /en-US/security-guidance/advisory/CVE-2021-43226
- Linkcisa.gov /known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-43226
sources
- CVE List (CVE.org): description, affected versions, references; CVE Terms of Use
- NVD: CVSS and CPE data
- CISA KEV catalog: exploitation, date added, due date
- CISA Vulnrichment (ADP): SSVC decision points
- FIRST EPSS: exploit probability and percentile
- PoC-in-GitHub: GitHub repositories that claim a proof of concept
- Summary, impact and triage tags: written by our AI analysis pipeline from the sources above. Check them against the sources.