Summary
Impact: Elevation of Privilege. Microsoft rating: Important. Not known to be exploited — Exploitation More Likely. Customer action: Required.
Details
According to the CVSS metric, the attack complexity is high (AC:H). What does that mean for this vulnerability?
Successful exploitation of this vulnerability requires an attacker to win a race condition.
According to the CVSS metric, a successful exploitation could lead to a scope change (S:C). What does this mean for this vulnerability?
This vulnerability could lead to a browser sandbox escape.
What privileges could be gained by an attacker who successfully exploited this vulnerability?
An attacker who successfully exploited this vulnerability could gain SYSTEM privileges.
Security updates
10.0.17763.8389 — https://support.microsoft.com/help/5075904
10.0.20348.4773 — https://support.microsoft.com/help/5075906
10.0.20348.4711 — https://support.microsoft.com/help/5075943
10.0.19044.6937 — https://support.microsoft.com/help/5075912
10.0.26100.32370 — https://support.microsoft.com/help/5075899
10.0.26100.32313 — https://support.microsoft.com/help/5075942
10.0.26200.7840 — https://support.microsoft.com/help/5077181
10.0.26200.7781 — https://support.microsoft.com/help/5077212
10.0.22631.6649 — https://support.microsoft.com/help/5075941
10.0.25398.2149 — https://support.microsoft.com/help/5075897
10.0.14393.8868 — https://support.microsoft.com/help/5075999
6.2.9200.25923 — https://support.microsoft.com/help/5075971
6.3.9600.23022 — https://support.microsoft.com/help/5075970
10.0.28000.1575 — https://support.microsoft.com/help/5077179
Vulnerabilities 1
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High 7.8
Windows Kernel Elevation of Privilege Vulnerability
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Kernel allows an authorized attacker to elevate privileges locally.
Revision history
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#1
Information published.
References
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CVE-2026-21231 Windows Kernel Elevation of Privilege Vulnerability - HTML
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21231
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Microsoft Exploitability Index
https://www.microsoft.com/en-us/msrc/exploitability-index?rtc=1
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Microsoft Support Lifecycle
https://support.microsoft.com/lifecycle
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Common Vulnerability Scoring System
https://www.first.org/cvss