CVE-2026-20927: 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.
Other sources
Windows SMB Server Denial of Service Vulnerability
— Microsoft
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 6.3.9600.22968Patch KB5073696 - Upgrade
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Fixed in 6.1.7601.28117Patch KB5073699 - Upgrade
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Fixed in 6.2.9200.25868Patch KB5073698 - Upgrade
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Fixed in 6.0.6003.23717Patch KB5073700 - Upgrade
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Fixed in 10.0.14393.8783Patch KB5073722 - Upgrade
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Fixed in 10.0.26100.32230Patch KB5073379 - Upgrade
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Fixed in 10.0.26100.7623Patch KB5074109 - Upgrade
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Fixed in 10.0.25398.2092Patch KB5073450 - Upgrade
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Fixed in 10.0.22631.6491Patch KB5073455 - Upgrade
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Fixed in 10.0.19045.6809Patch KB5073724 - Upgrade
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Fixed in 10.0.26200.7623Patch KB5074109 - Upgrade
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Fixed in 10.0.19044.6809Patch KB5073724 - Upgrade
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Fixed in 10.0.17763.8276Patch KB5073723 - Upgrade
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Fixed in 10.0.20348.4648Patch KB5073457
Event History
Frequently Asked Questions
What is the severity of CVE-2026-20927?
The severity of CVE-2026-20927 is critical as it allows an authorized attacker to cause a denial of service on the Windows SMB Server.
How do I fix CVE-2026-20927?
To fix CVE-2026-20927, install the relevant security patches provided by Microsoft for the affected versions of Windows Server and Windows.
What software is affected by CVE-2026-20927?
CVE-2026-20927 affects various versions of Windows Server 2008, 2012, 2016, 2019, and 2025, as well as Windows 10 and Windows 11.
What types of attacks does CVE-2026-20927 facilitate?
CVE-2026-20927 facilitates denial of service attacks by exploiting a race condition in the Windows SMB Server.
Is there a workaround for CVE-2026-20927?
Currently, Microsoft recommends applying the available security updates as the primary method to mitigate CVE-2026-20927.