CVE-2021-40449

Microsoft Windows Win32k Privilege Escalation

7.8 HIGHActively exploited (CISA KEV)Used in ransomwarePublic exploitEPSS 74.1%

Published12 Oct 2021
Added to CISA KEV17 Nov 2021
Remediation due1 Dec 2021

Description

Win32k Elevation of Privilege Vulnerability

CVSS 3.1 breakdown

Attack vectorLocal

Attack complexityLow

Privileges requiredLow

User interactionNone

ScopeUnchanged

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

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

Affected products

Microsoft Windows 10 1507< 10.0.10240.19086

Microsoft Windows 10 1607< 10.0.14393.4704

Microsoft Windows 10 1809< 10.0.17763.2237

Microsoft Windows 10 1909< 10.0.18363.1854

Microsoft Windows 10 2004< 10.0.19041.1288

Microsoft Windows 10 20h2< 10.0.19041.1288

Microsoft Windows 10 21h1< 10.0.19041.1288

Microsoft Windows 11all versions

Microsoft Windows 11 21h2< 10.0.22000.258

Microsoft Windows 7all versions

Microsoft Windows 8.1all versions

Microsoft Windows Rt 8.1all versions

Microsoft Windows Server 2004< 10.0.19041.1288

Microsoft Windows Server 2008r2

Microsoft Windows Server 2012r2

Microsoft Windows Server 2016< 10.0.14393.4704

Microsoft Windows Server 2019< 10.0.17763.2237

Microsoft Windows Server 2022< 10.0.20348.288

Microsoft Windows Server 20h2< 10.0.19042.1288

Remediation

Fixed in

Microsoft Windows 10 1507≥ 10.0.10240.19086

Microsoft Windows 10 1607≥ 10.0.14393.4704

Microsoft Windows 10 1809≥ 10.0.17763.2237

Microsoft Windows 10 1909≥ 10.0.18363.1854

Microsoft Windows 10 2004≥ 10.0.19041.1288

Microsoft Windows 10 20h2≥ 10.0.19041.1288

Microsoft Windows 10 21h1≥ 10.0.19041.1288

Microsoft Windows 11 21h2≥ 10.0.22000.258

Microsoft Windows Server 2004≥ 10.0.19041.1288

Microsoft Windows Server 2016≥ 10.0.14393.4704

Patch & vendor advisories

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-40449

References

http://packetstormsecurity.com/files/164926/Win32k-NtGdiResetDC-Use-After-Free-Local-Privilege-Escalation.htmlExploitThird Party AdvisoryVDB Entry
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-40449PatchVendor Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-40449US Government Resource

Related CVEs

Recent high-severity vulnerabilities sharing a weakness type.

Frequently asked

Is CVE-2021-40449 being actively exploited?

Yes. CVE-2021-40449 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added 17 Nov 2021. It has been used in ransomware campaigns.

How severe is CVE-2021-40449?

CVE-2021-40449 has a CVSS 3.1 base score of 7.8, rated high. EPSS estimates a 74.1% probability of exploitation.

Which products are affected by CVE-2021-40449?

Affected products include Microsoft Windows 10 1507, Microsoft Windows 10 1607, Microsoft Windows 10 1809, Microsoft Windows 10 1909, Microsoft Windows 10 2004, and 14 more.

How do I fix CVE-2021-40449?

Upgrade affected software to a fixed version, for example Microsoft Windows 10 1507 10.0.10240.19086, Microsoft Windows 10 1607 10.0.14393.4704, Microsoft Windows 10 1809 10.0.17763.2237 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2021-40449 against the real software inventory on every managed device, as each hourly inventory arrives. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. Because it is on the CISA KEV list, a risk for it never ranks below high, and the update that fixes it moves to the Emergency patch lane. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.