Reference page — cumulative record through Sunday, October 4, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2021-26863

CVE-2021-26863HIGH

Microsoft Windows 10 Version 1803 — Windows Win32k Elevation of Privilege Vulnerability

  AV  AC  PR  UI  S  C  I  A   CVSS    EPSS   %ile   KEV
   L   H   L   N  U  H  H  H    7.0   .1185   96.0     —

AFFECTED
  Product                                         Versions        Fixed
  Windows 10 Version 1803                         10.0.0 –        —
  Windows 10 Version 1809                         10.0.17763.0 –  —
  Windows 10 Version 1809                         10.0.0 –        —
  Windows 10 Version 1909                         10.0.0 –        —
  Windows 10 Version 2004                         10.0.0 –        —
  Windows 10 Version 20H2                         10.0.0 –        —
  Windows Server 2019                             10.0.17763.0 –  —
  Windows Server 2019 (Server Core installation)  10.0.17763.0 –  —
  Windows Server version 2004                     10.0.0 –        —
  Windows Server version 20H2                     10.0.0 –        —
  + 1 more

TIMELINE
  Feb 8   Reserved by microsoft
  Mar 11  Published (CNA: microsoft)
  Aug 19  EXPLOIT PUBLISHED — CVE-2021-26863 (Microsoft Windows 10 Version 1803). Public exploit reference added.

CWE-269 · CNA: microsoft · CVSS v3.1 · 3 references · NVD status: Modified

Description

Windows Win32k Elevation of Privilege Vulnerability

Lifecycle

Complete event history — 3 events, chronological
Date	Event	Detail
February 8, 2021	Reserved	Reserved by microsoft
March 11, 2021	Published	Published (CNA: microsoft)
August 19, 2026	EXPLOIT PUBLISHED	EXPLOIT PUBLISHED — CVE-2021-26863 (Microsoft Windows 10 Version 1803). Public exploit reference added.

Affected

Affected products and packages — 11 rows
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
Microsoft	Windows 10 Version 1803	—	10.0.0	—
Microsoft	Windows 10 Version 1809	—	10.0.17763.0	—
Microsoft	Windows 10 Version 1809	—	10.0.0	—
Microsoft	Windows 10 Version 1909	—	10.0.0	—
Microsoft	Windows 10 Version 2004	—	10.0.0	—
Microsoft	Windows 10 Version 20H2	—	10.0.0	—
Microsoft	Windows Server 2019	—	10.0.17763.0	—
Microsoft	Windows Server 2019 (Server Core installation)	—	10.0.17763.0	—
Microsoft	Windows Server version 2004	—	10.0.0	—
Microsoft	Windows Server version 20H2	—	10.0.0	—
Microsoft	Windows Server, version 1909 (Server Core installation)	—	10.0.0	—

Weaknesses

CWE-269

References (3)

http://packetstormsecurity.com/files/161768/Microsoft-Windows-Kernel-NtGdiGetDeviceCapsAll-Race-Condition-Use-After-Free.html [Exploit, Third Party Advisory]
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-26863
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26863 [Patch, Vendor Advisory]

Authoritative record: CVE-2021-26863 at cve.org

Vendors: microsoft

Weaknesses: CWE-269

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2021-26863 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Sunday, October 4, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.