Summary
Impact: Denial of Service. Microsoft rating: Important. Not known to be exploited — Exploitation Unlikely. 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.
Security updates
10.0.17763.8276 — https://support.microsoft.com/help/5073723
10.0.20348.4648 — https://support.microsoft.com/help/5073457
10.0.19044.6809 — https://support.microsoft.com/help/5073724
10.0.26100.32230 — https://support.microsoft.com/en-us/topic/a6021fd2-b3b7-45a7-b68e-35c28a2a77da
10.0.26200.7623 — https://support.microsoft.com/help/5074109
10.0.22631.6491 — https://support.microsoft.com/help/5073455
10.0.25398.2092 — https://support.microsoft.com/help/5073450
10.0.14393.8783 — https://support.microsoft.com/help/5073722
6.0.6003.23717 — https://support.microsoft.com/help/5073697
6.0.6003.23717 — https://support.microsoft.com/help/5073700
6.1.7601.28117 — https://support.microsoft.com/help/5073695
6.1.7601.28117 — https://support.microsoft.com/help/5073699
6.2.9200.25868 — https://support.microsoft.com/help/5073698
6.3.9600.22968 — https://support.microsoft.com/help/5073696
Vulnerabilities 1
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Medium 5.3
Windows SMB Server Denial of Service Vulnerability
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows SMB Server allows an authorized attacker to deny service over a network.
Revision history
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#1
Information published.
References
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CVE-2026-20927 Windows SMB Server Denial of Service Vulnerability - HTML
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20927
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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