CVE record · CVE-2021-38634

Microsoft Windows Update Client Elevation of Privilege Vulnerability

CVSS 7.1 HighEPSS 0.0087 · 58th percentile

Published by the CVE Program (CNA: microsoft) at 15 Sept 2021, 11:23 UTC. agentprime has not analysed this yet, so whether it affects any app is not known. This CVE names a vendor and product rather than a package, so the lockfile check doesn’t match it.

Affected products, as the CNA wrote them
Vendor	Product	Versions
Microsoft	Windows 10 Version 1507	affected 10.0.10240.0 to before 10.0.10240.19060 custom
Microsoft	Windows 10 Version 1607	affected 10.0.14393.0 to before 10.0.14393.4651 custom
Microsoft	Windows 10 Version 1809	affected 10.0.17763.0 to before 10.0.17763.2183 custom
Microsoft	Windows 10 Version 1809	affected 10.0.0 to before 10.0.17763.2183 custom
Microsoft	Windows 10 Version 1909	affected 10.0.0 to before 10.0.18363.1801 custom
Microsoft	Windows 10 Version 2004	affected 10.0.0 to before 10.0.19041.1237 custom
Microsoft	Windows 10 Version 20H2	affected 10.0.0 to before 10.0.19042.1237 custom
Microsoft	Windows 10 Version 21H1	affected 10.0.0 to before 10.0.19043.1237 custom
Microsoft	Windows Server 2016	affected 10.0.14393.0 to before 10.0.14393.4651 custom
Microsoft	Windows Server 2016 (Server Core installation)	affected 10.0.14393.0 to before 10.0.14393.4651 custom
Microsoft	Windows Server 2019	affected 10.0.17763.0 to before 10.0.17763.2183 custom
Microsoft	Windows Server 2019 (Server Core installation)	affected 10.0.17763.0 to before 10.0.17763.2183 custom
Microsoft	Windows Server 2022	affected 10.0.20348.0 to before 10.0.20348.230 custom
Microsoft	Windows Server version 2004	affected 10.0.0 to before 10.0.19041.1237 custom
Microsoft	Windows Server version 20H2	affected 10.0.0 to before 10.0.19042.1237 custom

Identifiers: CVE-2021-38634
CNA: microsoft
Tags: Microsoft Windows 10 Version 1507
Microsoft Windows 10 Version 1607
Microsoft Windows 10 Version 1809
Microsoft Windows 10 Version 1909
Microsoft Windows 10 Version 2004
Microsoft Windows 10 Version 20H2
Microsoft Windows 10 Version 21H1
Microsoft Windows Server 2016
Published: 15 Sept 2021
Updated: 10 Aug 2026

Not analysed yet

We haven’t published our own analysis of this CVE. If a person reviews it, this page will say what’s affected and what has to be true for it to matter.

Severity and exploitation

Score	Rating	CVSS	Vector	Source
7.1	High	3.1	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H/E:U/RL:O/RC:C	CNA (microsoft)

CISA KEV Not listed.
EPSS 0.0087, the 58th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

This record came from the full history of the CVE Program, published 15 Sept 2021. New records show when each source confirmed them.

Sources

References from the CNA

msrc.microsoft.com/update-guide/vulnerability/CVE-2021-38634 vendor-advisorypatch

Facts on this page come from the CVE List as the CNA published them, with CVSS from the sources named above, CISA KEV and FIRST EPSS. Vendors, products and versions are shown as the CNA wrote them. We don’t reproduce the CVE’s description.