CVE-2021-43226

Microsoft Windows: Privilege Escalation

As of , CVE-2021-43226 in Microsoft Windows is on CISA's list of exploited vulnerabilities: CISA listed it on . Our patch-first group: Patch this week.

Exploited
Yes: CISA listed it on 6 October 2025
US federal deadline
27 October 202521 days after CISA listed it. US federal civilian agencies must fix it by then.
Used in ransomware campaigns
KnownCISA changed it from Unknown to Known on 21 August 2026.
EPSS score
0.03Higher than 87% of the CVEs EPSS scores. EPSS estimates the chance of exploitation activity in the next 30 days.
Public exploit
None foundNeither Metasploit nor Exploit-DB lists one.
Fix
Vendor advice: msrc.microsoft.comLinks below, from CISA's entry.

What CISA says to do

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 required action

What the flaw is

Microsoft Windows Common Log File System Driver contains a privilege escalation vulnerability that could allow a local, privileged attacker to bypass certain security mechanisms.

CISA's description

Windows Common Log File System Driver Elevation of Privilege Vulnerability

The CVE record's description, from microsoft

CVE published
15 December 2021
Assigned by
microsoft
CVSS
7.8 High (CVSS 3.1, from the CNA)
CISA SSVC, exploitation
active
CISA SSVC, automatable
no
CISA SSVC, technical impact
total

Timeline

  1. The CVE record was published.
  2. CISA added it to its list of exploited vulnerabilities.
  3. The US federal deadline to fix it.
  4. CISA changed its entry. Ransomware use: Unknown to Known.

Windows: other exploited entries

VulnerabilityProductOur groupListedDeadlineEPSS
CVE-2025-60710Link FollowingMicrosoft WindowsPatch nowRansomware use, listed within a year0.05
CVE-2008-4250Buffer OverflowMicrosoft WindowsPatch this weekMetasploit module; EPSS 0.99; verified Exploit-DB entry0.99
CVE-2008-0015Video ActiveX Control Remote Code ExecutionMicrosoft WindowsPatch this weekMetasploit module; EPSS 0.77; verified Exploit-DB entry0.77
CVE-2013-3918Out-of-Bounds WriteMicrosoft WindowsPatch this weekMetasploit module; EPSS 0.74; verified Exploit-DB entry0.74
CVE-2010-2568Remote Code ExecutionMicrosoft WindowsPatch this weekMetasploit module; EPSS 0.91; verified Exploit-DB entry0.91
CVE-2015-0016TS WebProxy Directory TraversalMicrosoft WindowsPatch this weekMetasploit module; EPSS 0.76; verified Exploit-DB entry0.76
CVE-2015-2426Adobe Type Manager Library Remote Code ExecutionMicrosoft WindowsPatch this weekMetasploit module; EPSS 0.87; verified Exploit-DB entry0.87
CVE-2014-6332Object Linking & Embedding (OLE) Automation Array Remote Code ExecutionMicrosoft WindowsPatch this weekMetasploit module; EPSS 0.95; verified Exploit-DB entry0.95
CVE-2017-0146SMB Remote Code ExecutionMicrosoft WindowsPatch this weekRansomware use; Metasploit module; EPSS 0.90; verified Exploit-DB entry0.90
CVE-2014-4114Object Linking & Embedding (OLE) Remote Code ExecutionMicrosoft WindowsPatch this weekMetasploit module; EPSS 0.82; verified Exploit-DB entry0.82

All 174 entries for Windows

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