CVE-2021-33739

Microsoft Desktop Window Manager (DWM) Core Library Privilege Escalation

8.4 HIGHActively exploited (CISA KEV)EPSS 6.55%

Published8 Jun 2021
Added to CISA KEV3 Nov 2021
Remediation due17 Nov 2021

Description

Microsoft DWM Core Library Elevation of Privilege Vulnerability

CVSS 3.1 breakdown

Attack vectorLocal

Attack complexityLow

Privileges requiredNone

User interactionNone

ScopeUnchanged

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

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

Affected products

Microsoft Windows 10 1909< 10.0.18363.1621

Microsoft Windows 10 2004< 10.0.19041.1052

Microsoft Windows 10 20h2< 10.0.19042.1052

Microsoft Windows 10 21h1< 10.0.19043.1052

Microsoft Windows Server 2004< 10.0.19041.1052

Microsoft Windows Server 20h2< 10.0.19042.1052

Remediation

Fixed in

Microsoft Windows 10 1909≥ 10.0.18363.1621

Microsoft Windows 10 2004≥ 10.0.19041.1052

Microsoft Windows 10 20h2≥ 10.0.19042.1052

Microsoft Windows 10 21h1≥ 10.0.19043.1052

Microsoft Windows Server 2004≥ 10.0.19041.1052

Microsoft Windows Server 20h2≥ 10.0.19042.1052

Patch & vendor advisories

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-33739

References

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-33739PatchVendor Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-33739US Government Resource

Frequently asked

Is CVE-2021-33739 being actively exploited?

Yes. CVE-2021-33739 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added 3 Nov 2021.

How severe is CVE-2021-33739?

CVE-2021-33739 has a CVSS 3.1 base score of 8.4, rated high. EPSS estimates a 6.55% probability of exploitation.

Which products are affected by CVE-2021-33739?

Affected products include Microsoft Windows 10 1909, Microsoft Windows 10 2004, Microsoft Windows 10 20h2, Microsoft Windows 10 21h1, Microsoft Windows Server 2004, and 1 more.

How do I fix CVE-2021-33739?

Upgrade affected software to a fixed version, for example Microsoft Windows 10 1909 10.0.18363.1621, Microsoft Windows 10 2004 10.0.19041.1052, Microsoft Windows 10 20h2 10.0.19042.1052 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2021-33739 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.