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UK Cyber Defence
VulnerabilityAnalyzed

CVE-2021-33739

Microsoft Desktop Window Manager (DWM) Core Library Privilege Escalation Vulnerability

KEVHIGH 8.4EPSS 6.55%

Does this matter?

Known to be exploited in the wild (CISA KEV, CISA remediation deadline 17 November 2021). Treat as an emergency change: patch or isolate now, then hunt for prior compromise.

Description

Microsoft DWM Core Library Elevation of Privilege Vulnerability

CVSS 3.1
8.4 HIGHCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS
6.55% probability · 94th percentile
Public exploits
None in Exploit-DB
CISA KEV
Listed 3 November 2021 · due 17 November 2021
Affected
microsoft/windows 10 1909 · microsoft/windows 10 2004 · microsoft/windows 10 20h2 · microsoft/windows 10 21h1 · microsoft/windows server 2004 · microsoft/windows server 20h2
Source
secure@microsoft.com
EPSS trend
0%5%10%30 October 2026: 6.55%30 October 202630 October 2026

EPSS 6.6% since 30 October 2026; no change recorded yet. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”. Points are recorded when the score first appears and whenever it moves by a percentage point or more.

CISA notes

Apply updates per vendor instructions. https://nvd.nist.gov/vuln/detail/CVE-2021-33739

Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.