CVE-2021-41357Known exploitation

SYSTEM privilege escalation via undisclosed Win32k flaw

Published Oct 13, 2021 · Updated Oct 21, 2025

Elevation of privilege in Microsoft Windows Win32k allows local users with low privileges to gain SYSTEM access via a crafted application. Microsoft has not published the flawed Win32k operation or how the application triggers it. Successful exploitation requires local code execution and grants full control of the affected host.

CVSS severity7.8
High
EPSS probability2.08%
Next 30 days · Sep 16, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Elevation of privilege in Microsoft Windows Win32k allows local users with low privileges to gain SYSTEM access via a crafted application. Microsoft has not published the flawed Win32k operation or how the application triggers it. Successful exploitation requires local code execution and grants full control of the affected host.

The record

CVE
CVE-2021-41357
Published
Oct 13, 2021
Updated
Oct 21, 2025
Vendor
Microsoft
Product
Windows 10 Version 21H1
Classifications
T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 13, 2021CVE publishedPublication date reported by the CVE source.
  2. Oct 21, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=10.0.0 <10.0.19043.1288

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Microsoft · Windows 10 Version 21H1version=10.0.0 <10.0.19043.1288
Microsoft · Windows 11 version 21H2version=10.0.0 <10.0.22000.258
Microsoft · Windows Server, version 2004version=10.0.0 <10.0.19041.1288
Microsoft · Windows 10 Version 20H2version=10.0.0 <10.0.19042.1288
Microsoft · Windows Server version 20H2version=10.0.0 <10.0.19042.1288
Microsoft · Windows Server 2022version=10.0.0 <10.0.20348.288
Microsoft · Windows 10 Version 2004version=10.0.0 <10.0.19041.1288

Published CVSS scores

7.8Microsoft CorporationCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
4.6NIST NVDAV:L/AC:L/Au:N/C:P/I:P/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationReported
Public exploitUnconfirmed

Weakness, pattern, technique

T1068Exploitation for Privilege Escalation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Reported exploitation

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo