CVE-2021-33739 | Microsoft DWM Core Library Elevation of Privilege Vulnerability

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Microsoft DWM Core Library Elevation of Privilege Vulnerability

Published: 2021-06-08 Last update: 2025-10-30 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-33739 is rated Critical Active Threat (89.8/100): CVSS High severity, with high exploitation likelihood (EPSS 16.92%, 95th percentile). CISA KEV confirms active exploitation (added 2021-11-03) affecting Microsoft / Windows. Unauthenticated remote administrative access may be possible. The CISA remediation deadline has passed—treat as an emergency patch priority.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

CISA KEV Record for CVE-2021-33739

Name: Microsoft Desktop Window Manager (DWM) Core Library Privilege Escalation Vulnerability · CISA KEV detail

Exploit added: 2021-11-03

Action due: 2021-11-17

Required action: Apply updates per vendor instructions.

Exploit prediction scoring system (EPSS) score for CVE-2021-33739

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-22 18.99% 16.92% -2.07%
2 2026-04-07 18.88% 18.99% +0.12%
3 2026-03-17 — 18.88% —

Full EPSS history (30 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-33739

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
8.4 3.1 HIGH
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.5 5.9 [email protected]
7.8 3.1 HIGH
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 1.8 5.9 [email protected]
4.6 2.0 MEDIUM
AV:L/AC:L/Au:N/C:P/I:P/A:P Click to expand
Access vector (AV:L)
Requires local access to the target system.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 3.9 6.4 [email protected]

Weakness enumeration for CVE-2021-33739

Affected software / configurations for CVE-2021-33739

Vendor Product Version Raw CPE
microsoft windows_10_1909 < 10.0.18363.1621 cpe:2.3:o:microsoft:windows_10_1909:*:*:*:*:*:*:*:*
microsoft windows_10_2004 < 10.0.19041.1052 cpe:2.3:o:microsoft:windows_10_2004:*:*:*:*:*:*:*:*
microsoft windows_10_20h2 < 10.0.19042.1052 cpe:2.3:o:microsoft:windows_10_20h2:*:*:*:*:*:*:*:*
microsoft windows_10_21h1 < 10.0.19043.1052 cpe:2.3:o:microsoft:windows_10_21h1:*:*:*:*:*:*:*:*
microsoft windows_server_2004 < 10.0.19041.1052 cpe:2.3:o:microsoft:windows_server_2004:*:*:*:*:*:*:*:*
microsoft windows_server_20h2 < 10.0.19042.1052 cpe:2.3:o:microsoft:windows_server_20h2:*:*:*:*:*:*:*:*

References for CVE-2021-33739

cvelogic Threat Intelligence