CVE-2026-69777: Windows DHCP Client Elevation of Privilege Vulnerability

Severity: high (CVSS 8.0 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-122

Description

Heap-based buffer overflow in Windows DHCP Client allows an authorized attacker to elevate privileges over an adjacent network.

Affected products

Microsoft Windows 11: before 10.0.26100.9445 — fixed in 10.0.26100.9445
Microsoft Windows 11 25H2: before 10.0.26200.9445 — fixed in 10.0.26200.9445
Microsoft Windows 11 version 26H1: before 10.0.28000.2954 — fixed in 10.0.28000.2954
Microsoft Windows 11: from 10.0.26100.0 before 10.0.26100.9445 — fixed in 10.0.26100.9445
Microsoft Windows 11 25H2: from 10.0.26200.0 before 10.0.26200.9445 — fixed in 10.0.26200.9445
Microsoft Windows 11 version 26H1: from 10.0.28000.0 before 10.0.28000.2954 — fixed in 10.0.28000.2954

How to fix

Upgrade to a fixed version: Microsoft Windows 11 10.0.26100.9445; Microsoft Windows 11 25H2 10.0.26200.9445; Microsoft Windows 11 version 26H1 10.0.28000.2954; Microsoft Windows 11 10.0.26100.9445; Microsoft Windows 11 25H2 10.0.26200.9445; Microsoft Windows 11 version 26H1 10.0.28000.2954. Check the vendor advisory for mitigations.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-69777

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