high Known exploitedREV. 01

CVE-2021-43226Windows Common Log File System driver — escalation (2021)

The Common Log File System driver in Windows lets a local privileged attacker get past certain security mechanisms and raise privileges further. Microsoft's entry gives no detail, and no weakness class is recorded.

YOUR NEXT MOVE

Install the Microsoft update for this CVE now; ransomware crews use this driver family repeatedly, so prioritise hosts that lag on cumulative updates.

Read the risk

THE VITAL STATS
CVSS score
7.8/ 10
CVSS v3.1
EPSS probability
3%
Likelihood of exploitation
Attack complexity
Low
Conditions needed to exploit
Known exploited
Yes — CISA KEV
CVE published
2021-12-15
Added to KEV
2025-10-06
Exploit published
Not recorded
Confidence
medium
Kill chain
privilege escalation
MITRE ATT&CK
—
Severity
high

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Attacker needsA local account on the machine, described as already privileged.

Behind the card

3 REFERENCES
Field-level provenanceTRACE THE SOURCES +

Which source supports each field, when it was retrieved, and who extracted it.

FieldsSourceRetrievedExtractorConfidence
cvss, exploitation.attack_complexity, exploitation.exploit_available, references, published_atnvd.nist.gov2026-09-24scrty-crds-pipeline/0.1high
exploitation.known_exploited, exploitation.kev_addedcisa.gov2026-09-24scrty-crds-pipeline/0.1high
epssapi.first.org2026-09-24scrty-crds-pipeline/0.1high
title, summary, severity, remediation, mitre_attack, kill_chain, recommended_action, confidence, tags, exploitation.prerequisitesnvd.nist.gov2026-09-24claude-codehigh

Printing history

THE RECORD
  1. r1Initial base card

First printing. This card has not been reprinted since publication.

crds:cve-2021-43226 · CRDS 0.1 · Issued 2026-09-24