Summary
Impact: Information Disclosure. Microsoft rating: Important. Not known to be exploited — Exploitation Less Likely. Customer action: Required.
Details
What type of information could be disclosed by this vulnerability?
An attacker who successfully exploited this vulnerability could disclose uninitialized heap memory from a privileged process.
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.
Security updates
10.0.26300.9711 — https://support.microsoft.com/help/5127648
10.0.17763.9376 — https://support.microsoft.com/help/5126651
10.0.20348.5761 — https://support.microsoft.com/help/5126655
10.0.19044.7807 — https://support.microsoft.com/help/5126657
10.0.26100.33650 — https://support.microsoft.com/help/5126646
10.0.22631.7652 — https://support.microsoft.com/help/5126653
10.0.28000.3231 — https://support.microsoft.com/help/5127646
10.0.14393.9612 — https://support.microsoft.com/help/5126868
6.2.9200.26434 — https://support.microsoft.com/help/5126835
6.3.9600.23470 — https://support.microsoft.com/help/5126836
Vulnerabilities 1
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Medium 4.7
Windows Win32 Kernel Subsystem Information Disclosure Vulnerability
Exposure of sensitive system information to an unauthorized control sphere in Windows Win32 Kernel Subsystem allows an authorized attacker to disclose information locally.
Revision history
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#1
Information published.
References
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CVE-2026-83909 Windows Win32 Kernel Subsystem Information Disclosure Vulnerability - HTML
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-83909
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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