CVE-2026-69405: Windows DHCP Server Denial of Service Vulnerability

Severity: medium (CVSS 5.7 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-08 · updated 2026-10-31
Weakness: CWE-401

Description

Missing release of memory after effective lifetime in Windows DHCP Server allows an authorized attacker to deny service over an adjacent network.

Affected products

Microsoft Windows 10 1607: before 10.0.14393.9512 — fixed in 10.0.14393.9512
Microsoft Windows 10: before 10.0.17763.9245 — fixed in 10.0.17763.9245
Microsoft Windows Server 2012: r2
Microsoft Windows Server 2016: before 10.0.14393.9512 — fixed in 10.0.14393.9512
Microsoft Windows Server 2019: before 10.0.17763.9245 — fixed in 10.0.17763.9245
Microsoft Windows Server 2022: before 10.0.20348.5622 — fixed in 10.0.20348.5622
Microsoft Windows Server 2025: before 10.0.26100.33438 — fixed in 10.0.26100.33438
Microsoft Windows 10 1607: from 10.0.14393.0 before 10.0.14393.9512 — fixed in 10.0.14393.9512
Microsoft Windows 10: from 10.0.17763.0 before 10.0.17763.9245 — fixed in 10.0.17763.9245
Microsoft Windows Server 2012: from 6.2.9200.0 before 6.2.9200.26349 — fixed in 6.2.9200.26349
Microsoft Windows Server 2012 R2: from 6.3.9600.0 before 6.3.9600.23398 — fixed in 6.3.9600.23398
Microsoft Windows Server 2016: from 10.0.14393.0 before 10.0.14393.9512 — fixed in 10.0.14393.9512
Microsoft Windows Server 2019: from 10.0.17763.0 before 10.0.17763.9245 — fixed in 10.0.17763.9245
Microsoft Windows Server 2022: from 10.0.20348.0 before 10.0.20348.5622 — fixed in 10.0.20348.5622
Microsoft Windows Server 2025: from 10.0.26100.0 before 10.0.26100.33438 — fixed in 10.0.26100.33438

How to fix

Upgrade to a fixed version: Microsoft Windows 10 1607 10.0.14393.9512; Microsoft Windows 10 10.0.17763.9245; Microsoft Windows Server 2016 10.0.14393.9512; Microsoft Windows Server 2019 10.0.17763.9245; Microsoft Windows Server 2022 10.0.20348.5622; Microsoft Windows Server 2025 10.0.26100.33438; Microsoft Windows 10 1607 10.0.14393.9512; Microsoft Windows 10 10.0.17763.9245; Microsoft Windows Server 2012 6.2.9200.26349; Microsoft Windows Server 2012 R2 6.3.9600.23398; Microsoft Windows Server 2016 10.0.14393.9512; Microsoft Windows Server 2019 10.0.17763.9245. Check the vendor advisory for mitigations.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-69405

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